diff --git a/.idea/codeStyles/Project.xml b/.idea/codeStyles/Project.xml
index bb65b3e9..adf3548b 100644
--- a/.idea/codeStyles/Project.xml
+++ b/.idea/codeStyles/Project.xml
@@ -54,6 +54,9 @@
       <option name="TERNARY_OPERATION_WRAP" value="5" />
       <option name="TERNARY_OPERATION_SIGNS_ON_NEXT_LINE" value="true" />
       <option name="KEEP_SIMPLE_CLASSES_IN_ONE_LINE" value="true" />
+      <option name="ARRAY_INITIALIZER_WRAP" value="5" />
+      <option name="ARRAY_INITIALIZER_LBRACE_ON_NEXT_LINE" value="true" />
+      <option name="ARRAY_INITIALIZER_RBRACE_ON_NEXT_LINE" value="true" />
       <option name="ENUM_CONSTANTS_WRAP" value="2" />
     </codeStyleSettings>
     <codeStyleSettings language="XML">
diff --git a/lib/build.gradle.kts b/lib/build.gradle.kts
index 2e5feb3a..ca37c1f3 100644
--- a/lib/build.gradle.kts
+++ b/lib/build.gradle.kts
@@ -21,6 +21,12 @@ dependencies {
     implementation("org.slf4j", "slf4j-api", "2.0.3")
     implementation("org.xerial", "sqlite-jdbc", "3.39.3.0")
     implementation("com.zaxxer", "HikariCP", "5.0.1")
+
+    testImplementation("org.junit.jupiter", "junit-jupiter", "5.9.0")
+}
+
+tasks.named<Test>("test") {
+    useJUnitPlatform()
 }
 
 configurations {
diff --git a/lib/src/main/java/org/asamk/signal/manager/helper/IncomingMessageHandler.java b/lib/src/main/java/org/asamk/signal/manager/helper/IncomingMessageHandler.java
index 80cf7687..bd42ae5f 100644
--- a/lib/src/main/java/org/asamk/signal/manager/helper/IncomingMessageHandler.java
+++ b/lib/src/main/java/org/asamk/signal/manager/helper/IncomingMessageHandler.java
@@ -56,16 +56,19 @@ import org.whispersystems.signalservice.api.messages.SignalServiceEnvelope;
 import org.whispersystems.signalservice.api.messages.SignalServiceGroup;
 import org.whispersystems.signalservice.api.messages.SignalServiceGroupContext;
 import org.whispersystems.signalservice.api.messages.SignalServiceGroupV2;
+import org.whispersystems.signalservice.api.messages.SignalServicePniSignatureMessage;
 import org.whispersystems.signalservice.api.messages.SignalServiceReceiptMessage;
 import org.whispersystems.signalservice.api.messages.SignalServiceStoryMessage;
 import org.whispersystems.signalservice.api.messages.multidevice.SignalServiceSyncMessage;
 import org.whispersystems.signalservice.api.messages.multidevice.StickerPackOperationMessage;
+import org.whispersystems.signalservice.api.push.ACI;
 import org.whispersystems.signalservice.api.push.PNI;
 import org.whispersystems.signalservice.api.push.ServiceId;
 import org.whispersystems.signalservice.api.push.SignalServiceAddress;
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Optional;
 import java.util.stream.Collectors;
 
 public final class IncomingMessageHandler {
@@ -194,7 +197,18 @@ public final class IncomingMessageHandler {
         if (content != null) {
             // Store uuid if we don't have it already
             // address/uuid is validated by unidentified sender certificate
-            account.getRecipientTrustedResolver().resolveRecipientTrusted(content.getSender());
+
+            boolean handledPniSignature = false;
+            if (content.getPniSignatureMessage().isPresent()) {
+                final var message = content.getPniSignatureMessage().get();
+                final var senderAddress = getSenderAddress(envelope, content);
+                if (senderAddress != null) {
+                    handledPniSignature = handlePniSignatureMessage(message, senderAddress);
+                }
+            }
+            if (!handledPniSignature) {
+                account.getRecipientTrustedResolver().resolveRecipientTrusted(content.getSender());
+            }
         }
         if (envelope.isReceipt()) {
             final var senderDeviceAddress = getSender(envelope, content);
@@ -215,8 +229,9 @@ public final class IncomingMessageHandler {
             logger.info("Ignoring a message from blocked user/group: {}", envelope.getTimestamp());
             return List.of();
         } else if (notAllowedToSendToGroup) {
+            final var senderAddress = getSenderAddress(envelope, content);
             logger.info("Ignoring a group message from an unauthorized sender (no member or admin): {} {}",
-                    (envelope.hasSourceUuid() ? envelope.getSourceAddress() : content.getSender()).getIdentifier(),
+                    senderAddress == null ? null : senderAddress.getIdentifier(),
                     envelope.getTimestamp());
             return List.of();
         } else {
@@ -323,6 +338,32 @@ public final class IncomingMessageHandler {
         return actions;
     }
 
+    private boolean handlePniSignatureMessage(
+            final SignalServicePniSignatureMessage message, final SignalServiceAddress senderAddress
+    ) {
+        final var aci = ACI.from(senderAddress.getServiceId());
+        final var aciIdentity = account.getIdentityKeyStore().getIdentityInfo(aci);
+        final var pni = message.getPni();
+        final var pniIdentity = account.getIdentityKeyStore().getIdentityInfo(pni);
+
+        if (aciIdentity == null || pniIdentity == null || aci.equals(pni)) {
+            return false;
+        }
+
+        final var verified = pniIdentity.getIdentityKey()
+                .verifyAlternateIdentity(aciIdentity.getIdentityKey(), message.getSignature());
+
+        if (!verified) {
+            logger.debug("Invalid PNI signature of ACI {} with PNI {}", aci, pni);
+            return false;
+        }
+
+        logger.debug("Verified association of ACI {} with PNI {}", aci, pni);
+        account.getRecipientTrustedResolver()
+                .resolveRecipientTrusted(Optional.of(aci), Optional.of(pni), senderAddress.getNumber());
+        return true;
+    }
+
     private void handleDecryptionErrorMessage(
             final List<HandleAction> actions,
             final RecipientId sender,
@@ -585,12 +626,8 @@ public final class IncomingMessageHandler {
     }
 
     private boolean isMessageBlocked(SignalServiceEnvelope envelope, SignalServiceContent content) {
-        SignalServiceAddress source;
-        if (!envelope.isUnidentifiedSender() && envelope.hasSourceUuid()) {
-            source = envelope.getSourceAddress();
-        } else if (content != null) {
-            source = content.getSender();
-        } else {
+        SignalServiceAddress source = getSenderAddress(envelope, content);
+        if (source == null) {
             return false;
         }
         final var recipientId = context.getRecipientHelper().resolveRecipient(source);
@@ -608,12 +645,8 @@ public final class IncomingMessageHandler {
     }
 
     private boolean isNotAllowedToSendToGroup(SignalServiceEnvelope envelope, SignalServiceContent content) {
-        SignalServiceAddress source;
-        if (!envelope.isUnidentifiedSender() && envelope.hasSourceUuid()) {
-            source = envelope.getSourceAddress();
-        } else if (content != null) {
-            source = content.getSender();
-        } else {
+        SignalServiceAddress source = getSenderAddress(envelope, content);
+        if (source == null) {
             return false;
         }
 
@@ -853,6 +886,16 @@ public final class IncomingMessageHandler {
         this.account.getProfileStore().storeProfileKey(source, profileKey);
     }
 
+    private SignalServiceAddress getSenderAddress(SignalServiceEnvelope envelope, SignalServiceContent content) {
+        if (!envelope.isUnidentifiedSender() && envelope.hasSourceUuid()) {
+            return envelope.getSourceAddress();
+        } else if (content != null) {
+            return content.getSender();
+        } else {
+            return null;
+        }
+    }
+
     private DeviceAddress getSender(SignalServiceEnvelope envelope, SignalServiceContent content) {
         if (!envelope.isUnidentifiedSender() && envelope.hasSourceUuid()) {
             return new DeviceAddress(context.getRecipientHelper().resolveRecipient(envelope.getSourceAddress()),
diff --git a/lib/src/main/java/org/asamk/signal/manager/storage/AccountDatabase.java b/lib/src/main/java/org/asamk/signal/manager/storage/AccountDatabase.java
index 3c168860..c13be697 100644
--- a/lib/src/main/java/org/asamk/signal/manager/storage/AccountDatabase.java
+++ b/lib/src/main/java/org/asamk/signal/manager/storage/AccountDatabase.java
@@ -22,7 +22,7 @@ import java.sql.SQLException;
 public class AccountDatabase extends Database {
 
     private final static Logger logger = LoggerFactory.getLogger(AccountDatabase.class);
-    private static final long DATABASE_VERSION = 10;
+    private static final long DATABASE_VERSION = 11;
 
     private AccountDatabase(final HikariDataSource dataSource) {
         super(logger, DATABASE_VERSION, dataSource);
@@ -288,5 +288,13 @@ public class AccountDatabase extends Database {
                                         """);
             }
         }
+        if (oldVersion < 11) {
+            logger.debug("Updating database: Adding pni field");
+            try (final var statement = connection.createStatement()) {
+                statement.executeUpdate("""
+                                        ALTER TABLE recipient ADD COLUMN pni BLOB;
+                                        """);
+            }
+        }
     }
 }
diff --git a/lib/src/main/java/org/asamk/signal/manager/storage/SignalAccount.java b/lib/src/main/java/org/asamk/signal/manager/storage/SignalAccount.java
index db919269..1759649e 100644
--- a/lib/src/main/java/org/asamk/signal/manager/storage/SignalAccount.java
+++ b/lib/src/main/java/org/asamk/signal/manager/storage/SignalAccount.java
@@ -102,7 +102,7 @@ public class SignalAccount implements Closeable {
     private final static Logger logger = LoggerFactory.getLogger(SignalAccount.class);
 
     private static final int MINIMUM_STORAGE_VERSION = 1;
-    private static final int CURRENT_STORAGE_VERSION = 5;
+    private static final int CURRENT_STORAGE_VERSION = 6;
 
     private final Object LOCK = new Object();
 
@@ -634,6 +634,9 @@ public class SignalAccount implements Closeable {
                 migratedLegacyConfig = true;
             }
         }
+        if (previousStorageVersion < 6) {
+            getRecipientTrustedResolver().resolveSelfRecipientTrusted(getSelfRecipientAddress());
+        }
         final var legacyAciPreKeysPath = getAciPreKeysPath(dataPath, accountPath);
         if (legacyAciPreKeysPath.exists()) {
             LegacyPreKeyStore.migrate(legacyAciPreKeysPath, getAciPreKeyStore());
diff --git a/lib/src/main/java/org/asamk/signal/manager/storage/recipients/MergeRecipientHelper.java b/lib/src/main/java/org/asamk/signal/manager/storage/recipients/MergeRecipientHelper.java
new file mode 100644
index 00000000..0afde555
--- /dev/null
+++ b/lib/src/main/java/org/asamk/signal/manager/storage/recipients/MergeRecipientHelper.java
@@ -0,0 +1,140 @@
+package org.asamk.signal.manager.storage.recipients;
+
+import org.asamk.signal.manager.api.Pair;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.sql.SQLException;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+public class MergeRecipientHelper {
+
+    private final static Logger logger = LoggerFactory.getLogger(MergeRecipientHelper.class);
+
+    static Pair<RecipientId, List<RecipientId>> resolveRecipientTrustedLocked(
+            Store store, RecipientAddress address
+    ) throws SQLException {
+        // address has serviceId and number, optionally also pni
+
+        final var recipients = store.findAllByAddress(address);
+
+        if (recipients.isEmpty()) {
+            logger.debug("Got new recipient, serviceId, PNI and number are unknown");
+            return new Pair<>(store.addNewRecipient(address), List.of());
+        }
+
+        if (recipients.size() == 1) {
+            final var recipient = recipients.stream().findFirst().get();
+            if (recipient.address().hasIdentifiersOf(address)) {
+                return new Pair<>(recipient.id(), List.of());
+            }
+
+            if (recipient.address().serviceId().isEmpty() || (
+                    recipient.address().serviceId().equals(address.serviceId())
+            ) || (
+                    recipient.address().pni().isPresent() && recipient.address().pni().equals(address.serviceId())
+            ) || (
+                    recipient.address().serviceId().equals(address.pni())
+            ) || (
+                    address.pni().isPresent() && address.pni().equals(recipient.address().pni())
+            )) {
+                logger.debug("Got existing recipient {}, updating with high trust address", recipient.id());
+                store.updateRecipientAddress(recipient.id(), recipient.address().withIdentifiersFrom(address));
+                return new Pair<>(recipient.id(), List.of());
+            }
+
+            logger.debug(
+                    "Got recipient {} existing with number/pni, but different serviceId, so stripping its number and adding new recipient",
+                    recipient.id());
+            store.updateRecipientAddress(recipient.id(), recipient.address().removeIdentifiersFrom(address));
+
+            return new Pair<>(store.addNewRecipient(address), List.of());
+        }
+
+        var resultingRecipient = recipients.stream()
+                .filter(r -> r.address().serviceId().equals(address.serviceId()) || r.address()
+                        .pni()
+                        .equals(address.serviceId()))
+                .findFirst();
+        if (resultingRecipient.isEmpty() && address.pni().isPresent()) {
+            resultingRecipient = recipients.stream().filter(r -> r.address().serviceId().equals(address.pni()) || (
+                    address.serviceId().equals(address.pni()) && r.address().pni().equals(address.pni())
+            )).findFirst();
+        }
+
+        final Set<RecipientWithAddress> remainingRecipients;
+        if (resultingRecipient.isEmpty()) {
+            remainingRecipients = recipients;
+        } else {
+            remainingRecipients = new HashSet<>(recipients);
+            remainingRecipients.remove(resultingRecipient.get());
+        }
+
+        final var recipientsToBeMerged = new HashSet<RecipientWithAddress>();
+        final var recipientsToBeStripped = new HashSet<RecipientWithAddress>();
+        for (final var recipient : remainingRecipients) {
+            if (!recipient.address().hasAdditionalIdentifiersThan(address)) {
+                recipientsToBeMerged.add(recipient);
+                continue;
+            }
+
+            if (recipient.address().hasOnlyPniAndNumber()) {
+                // PNI and phone number are linked by the server
+                recipientsToBeMerged.add(recipient);
+                continue;
+            }
+
+            recipientsToBeStripped.add(recipient);
+        }
+
+        logger.debug("Got separate recipients for high trust identifiers {}, need to merge ({}) and strip ({})",
+                address,
+                recipientsToBeMerged.stream().map(r -> r.id().toString()).collect(Collectors.joining(", ")),
+                recipientsToBeStripped.stream().map(r -> r.id().toString()).collect(Collectors.joining(", ")));
+
+        RecipientAddress finalAddress = resultingRecipient.map(RecipientWithAddress::address).orElse(null);
+        for (final var recipient : recipientsToBeMerged) {
+            if (finalAddress == null) {
+                finalAddress = recipient.address();
+            } else {
+                finalAddress = finalAddress.withIdentifiersFrom(recipient.address());
+            }
+            store.removeRecipientAddress(recipient.id());
+        }
+        if (finalAddress == null) {
+            finalAddress = address;
+        } else {
+            finalAddress = finalAddress.withIdentifiersFrom(address);
+        }
+
+        for (final var recipient : recipientsToBeStripped) {
+            store.updateRecipientAddress(recipient.id(), recipient.address().removeIdentifiersFrom(address));
+        }
+
+        // Create fixed RecipientIds that won't update its id after merged
+        final var toBeMergedRecipientIds = recipientsToBeMerged.stream()
+                .map(r -> new RecipientId(r.id().id(), null))
+                .toList();
+
+        if (resultingRecipient.isPresent()) {
+            store.updateRecipientAddress(resultingRecipient.get().id(), finalAddress);
+            return new Pair<>(resultingRecipient.get().id(), toBeMergedRecipientIds);
+        }
+
+        return new Pair<>(store.addNewRecipient(finalAddress), toBeMergedRecipientIds);
+    }
+
+    public interface Store {
+
+        Set<RecipientWithAddress> findAllByAddress(final RecipientAddress address) throws SQLException;
+
+        RecipientId addNewRecipient(final RecipientAddress address) throws SQLException;
+
+        void updateRecipientAddress(RecipientId recipientId, final RecipientAddress address) throws SQLException;
+
+        void removeRecipientAddress(RecipientId recipientId) throws SQLException;
+    }
+}
diff --git a/lib/src/main/java/org/asamk/signal/manager/storage/recipients/RecipientAddress.java b/lib/src/main/java/org/asamk/signal/manager/storage/recipients/RecipientAddress.java
index c3b18299..7dc193a9 100644
--- a/lib/src/main/java/org/asamk/signal/manager/storage/recipients/RecipientAddress.java
+++ b/lib/src/main/java/org/asamk/signal/manager/storage/recipients/RecipientAddress.java
@@ -24,6 +24,14 @@ public record RecipientAddress(Optional<ServiceId> serviceId, Optional<PNI> pni,
         if (serviceId.isEmpty() && pni.isPresent()) {
             serviceId = Optional.of(pni.get());
         }
+        if (serviceId.isPresent() && serviceId.get() instanceof PNI sPNI) {
+            if (pni.isPresent() && !sPNI.equals(pni.get())) {
+                throw new AssertionError("Must not have two different PNIs!");
+            }
+            if (pni.isEmpty()) {
+                pni = Optional.of(sPNI);
+            }
+        }
         if (serviceId.isEmpty() && number.isEmpty()) {
             throw new AssertionError("Must have either a ServiceId or E164 number!");
         }
@@ -49,6 +57,22 @@ public record RecipientAddress(Optional<ServiceId> serviceId, Optional<PNI> pni,
         this(Optional.of(serviceId), Optional.empty());
     }
 
+    public RecipientAddress withIdentifiersFrom(RecipientAddress address) {
+        return new RecipientAddress((
+                this.serviceId.isEmpty() || this.isServiceIdPNI() || this.serviceId.equals(address.pni)
+        ) && !address.isServiceIdPNI() ? address.serviceId : this.serviceId,
+                address.pni.or(this::pni),
+                address.number.or(this::number));
+    }
+
+    public RecipientAddress removeIdentifiersFrom(RecipientAddress address) {
+        return new RecipientAddress(address.serviceId.equals(this.serviceId) || address.pni.equals(this.serviceId)
+                ? Optional.empty()
+                : this.serviceId,
+                address.pni.equals(this.pni) || address.serviceId.equals(this.pni) ? Optional.empty() : this.pni,
+                address.number.equals(this.number) ? Optional.empty() : this.number);
+    }
+
     public ServiceId getServiceId() {
         return serviceId.orElse(ServiceId.UNKNOWN);
     }
@@ -89,6 +113,42 @@ public record RecipientAddress(Optional<ServiceId> serviceId, Optional<PNI> pni,
         );
     }
 
+    public boolean hasSingleIdentifier() {
+        return serviceId().isEmpty() || number.isEmpty();
+    }
+
+    public boolean hasIdentifiersOf(RecipientAddress address) {
+        return (address.serviceId.isEmpty() || address.serviceId.equals(serviceId) || address.serviceId.equals(pni))
+                && (address.pni.isEmpty() || address.pni.equals(pni))
+                && (address.number.isEmpty() || address.number.equals(number));
+    }
+
+    public boolean hasAdditionalIdentifiersThan(RecipientAddress address) {
+        return (
+                serviceId.isPresent() && (
+                        address.serviceId.isEmpty() || (
+                                !address.serviceId.equals(serviceId) && !address.pni.equals(serviceId)
+                        )
+                )
+        ) || (
+                pni.isPresent() && !address.serviceId.equals(pni) && (
+                        address.pni.isEmpty() || !address.pni.equals(pni)
+                )
+        ) || (
+                number.isPresent() && (
+                        address.number.isEmpty() || !address.number.equals(number)
+                )
+        );
+    }
+
+    public boolean hasOnlyPniAndNumber() {
+        return pni.isPresent() && serviceId.equals(pni) && number.isPresent();
+    }
+
+    public boolean isServiceIdPNI() {
+        return serviceId.isPresent() && (pni.isPresent() && serviceId.equals(pni));
+    }
+
     public SignalServiceAddress toSignalServiceAddress() {
         return new SignalServiceAddress(getServiceId(), number);
     }
diff --git a/lib/src/main/java/org/asamk/signal/manager/storage/recipients/RecipientStore.java b/lib/src/main/java/org/asamk/signal/manager/storage/recipients/RecipientStore.java
index 1b601980..81470e83 100644
--- a/lib/src/main/java/org/asamk/signal/manager/storage/recipients/RecipientStore.java
+++ b/lib/src/main/java/org/asamk/signal/manager/storage/recipients/RecipientStore.java
@@ -53,6 +53,7 @@ public class RecipientStore implements RecipientIdCreator, RecipientResolver, Re
                                       _id INTEGER PRIMARY KEY AUTOINCREMENT,
                                       number TEXT UNIQUE,
                                       uuid BLOB UNIQUE,
+                                      pni BLOB UNIQUE,
                                       profile_key BLOB,
                                       profile_key_credential BLOB,
 
@@ -92,7 +93,7 @@ public class RecipientStore implements RecipientIdCreator, RecipientResolver, Re
     public RecipientAddress resolveRecipientAddress(RecipientId recipientId) {
         final var sql = (
                 """
-                SELECT r.number, r.uuid
+                SELECT r.number, r.uuid, r.pni
                 FROM %s r
                 WHERE r._id = ?
                 """
@@ -246,7 +247,7 @@ public class RecipientStore implements RecipientIdCreator, RecipientResolver, Re
             final Optional<ACI> aci, final Optional<PNI> pni, final Optional<String> number
     ) {
         final var serviceId = aci.map(a -> (ServiceId) a).or(() -> pni);
-        return resolveRecipientTrusted(new RecipientAddress(serviceId, number), false);
+        return resolveRecipientTrusted(new RecipientAddress(serviceId, pni, number), false);
     }
 
     @Override
@@ -308,7 +309,7 @@ public class RecipientStore implements RecipientIdCreator, RecipientResolver, Re
         final var sql = (
                 """
                 SELECT r._id,
-                       r.number, r.uuid,
+                       r.number, r.uuid, r.pni,
                        r.profile_key, r.profile_key_credential,
                        r.given_name, r.family_name, r.expiration_time, r.profile_sharing, r.color, r.blocked, r.archived,
                        r.profile_last_update_timestamp, r.profile_given_name, r.profile_family_name, r.profile_about, r.profile_about_emoji, r.profile_avatar_url_path, r.profile_mobile_coin_address, r.profile_unidentified_access_mode, r.profile_capabilities
@@ -601,21 +602,33 @@ public class RecipientStore implements RecipientIdCreator, RecipientResolver, Re
     }
 
     private RecipientId resolveRecipientTrusted(RecipientAddress address, boolean isSelf) {
-        final Pair<RecipientId, Optional<RecipientId>> pair;
+        final Pair<RecipientId, List<RecipientId>> pair;
         synchronized (recipientsLock) {
             try (final var connection = database.getConnection()) {
                 connection.setAutoCommit(false);
-                pair = resolveRecipientTrustedLocked(connection, address, isSelf);
+                if (address.hasSingleIdentifier() || (
+                        !isSelf && selfAddressProvider.getSelfAddress().matches(address)
+                )) {
+                    pair = new Pair<>(resolveRecipientLocked(connection, address), List.of());
+                } else {
+                    pair = MergeRecipientHelper.resolveRecipientTrustedLocked(new HelperStore(connection), address);
+
+                    for (final var toBeMergedRecipientId : pair.second()) {
+                        mergeRecipientsLocked(connection, pair.first(), toBeMergedRecipientId);
+                    }
+                }
                 connection.commit();
             } catch (SQLException e) {
                 throw new RuntimeException("Failed update recipient store", e);
             }
         }
 
-        if (pair.second().isPresent()) {
+        if (pair.second().size() > 0) {
             try (final var connection = database.getConnection()) {
-                recipientMergeHandler.mergeRecipients(connection, pair.first(), pair.second().get());
-                deleteRecipient(connection, pair.second().get());
+                for (final var toBeMergedRecipientId : pair.second()) {
+                    recipientMergeHandler.mergeRecipients(connection, pair.first(), toBeMergedRecipientId);
+                    deleteRecipient(connection, toBeMergedRecipientId);
+                }
             } catch (SQLException e) {
                 throw new RuntimeException("Failed update recipient store", e);
             }
@@ -623,82 +636,6 @@ public class RecipientStore implements RecipientIdCreator, RecipientResolver, Re
         return pair.first();
     }
 
-    private Pair<RecipientId, Optional<RecipientId>> resolveRecipientTrustedLocked(
-            Connection connection, RecipientAddress address, boolean isSelf
-    ) throws SQLException {
-        if (!isSelf) {
-            if (selfAddressProvider.getSelfAddress().matches(address)) {
-                return new Pair<>(resolveRecipientLocked(connection, address), Optional.empty());
-            }
-        }
-        final var byNumber = address.number().isEmpty()
-                ? Optional.<RecipientWithAddress>empty()
-                : findByNumber(connection, address.number().get());
-        final var byUuid = address.serviceId().isEmpty()
-                ? Optional.<RecipientWithAddress>empty()
-                : findByServiceId(connection, address.serviceId().get());
-
-        if (byNumber.isEmpty() && byUuid.isEmpty()) {
-            logger.debug("Got new recipient, both uuid and number are unknown");
-            return new Pair<>(addNewRecipient(connection, address), Optional.empty());
-        }
-
-        if (address.serviceId().isEmpty() || address.number().isEmpty() || byNumber.equals(byUuid)) {
-            return new Pair<>(byUuid.or(() -> byNumber).map(RecipientWithAddress::id).get(), Optional.empty());
-        }
-
-        if (byNumber.isEmpty()) {
-            logger.debug("Got recipient {} existing with uuid, updating with high trust number", byUuid.get().id());
-            updateRecipientAddress(connection, byUuid.get().id(), address);
-            return new Pair<>(byUuid.get().id(), Optional.empty());
-        }
-
-        final var byNumberRecipient = byNumber.get();
-
-        if (byUuid.isEmpty()) {
-            if (byNumberRecipient.address().serviceId().isPresent()) {
-                logger.debug(
-                        "Got recipient {} existing with number, but different uuid, so stripping its number and adding new recipient",
-                        byNumberRecipient.id());
-
-                updateRecipientAddress(connection,
-                        byNumberRecipient.id(),
-                        new RecipientAddress(byNumberRecipient.address().serviceId().get()));
-                return new Pair<>(addNewRecipient(connection, address), Optional.empty());
-            }
-
-            logger.debug("Got recipient {} existing with number and no uuid, updating with high trust uuid",
-                    byNumberRecipient.id());
-            updateRecipientAddress(connection, byNumberRecipient.id(), address);
-            return new Pair<>(byNumberRecipient.id(), Optional.empty());
-        }
-
-        final var byUuidRecipient = byUuid.get();
-
-        if (byNumberRecipient.address().serviceId().isPresent()) {
-            logger.debug(
-                    "Got separate recipients for high trust number {} and uuid {}, recipient for number has different uuid, so stripping its number",
-                    byNumberRecipient.id(),
-                    byUuidRecipient.id());
-
-            updateRecipientAddress(connection,
-                    byNumberRecipient.id(),
-                    new RecipientAddress(byNumberRecipient.address().serviceId().get()));
-            updateRecipientAddress(connection, byUuidRecipient.id(), address);
-            return new Pair<>(byUuidRecipient.id(), Optional.empty());
-        }
-
-        logger.debug("Got separate recipients for high trust number {} and uuid {}, need to merge them",
-                byNumberRecipient.id(),
-                byUuidRecipient.id());
-        // Create a fixed RecipientId that won't update its id after merge
-        final var toBeMergedRecipientId = new RecipientId(byNumberRecipient.id().id(), null);
-        mergeRecipientsLocked(connection, byUuidRecipient.id(), toBeMergedRecipientId);
-        removeRecipientAddress(connection, toBeMergedRecipientId);
-        updateRecipientAddress(connection, byUuidRecipient.id(), address);
-        return new Pair<>(byUuidRecipient.id(), Optional.of(toBeMergedRecipientId));
-    }
-
     private RecipientId resolveRecipientLocked(
             Connection connection, RecipientAddress address
     ) throws SQLException {
@@ -762,13 +699,14 @@ public class RecipientStore implements RecipientIdCreator, RecipientResolver, Re
     ) throws SQLException {
         final var sql = (
                 """
-                INSERT INTO %s (number, uuid)
-                VALUES (?, ?)
+                INSERT INTO %s (number, uuid, pni)
+                VALUES (?, ?, ?)
                 """
         ).formatted(TABLE_RECIPIENT);
         try (final var statement = connection.prepareStatement(sql)) {
             statement.setString(1, address.number().orElse(null));
             statement.setBytes(2, address.serviceId().map(ServiceId::uuid).map(UuidUtil::toByteArray).orElse(null));
+            statement.setBytes(3, address.pni().map(PNI::uuid).map(UuidUtil::toByteArray).orElse(null));
             statement.executeUpdate();
             final var generatedKeys = statement.getGeneratedKeys();
             if (generatedKeys.next()) {
@@ -785,7 +723,7 @@ public class RecipientStore implements RecipientIdCreator, RecipientResolver, Re
         final var sql = (
                 """
                 UPDATE %s
-                SET number = NULL, uuid = NULL
+                SET number = NULL, uuid = NULL, pni = NULL
                 WHERE _id = ?
                 """
         ).formatted(TABLE_RECIPIENT);
@@ -801,14 +739,15 @@ public class RecipientStore implements RecipientIdCreator, RecipientResolver, Re
         final var sql = (
                 """
                 UPDATE %s
-                SET number = ?, uuid = ?
+                SET number = ?, uuid = ?, pni = ?
                 WHERE _id = ?
                 """
         ).formatted(TABLE_RECIPIENT);
         try (final var statement = connection.prepareStatement(sql)) {
             statement.setString(1, address.number().orElse(null));
             statement.setBytes(2, address.serviceId().map(ServiceId::uuid).map(UuidUtil::toByteArray).orElse(null));
-            statement.setLong(3, recipientId.id());
+            statement.setBytes(3, address.pni().map(PNI::uuid).map(UuidUtil::toByteArray).orElse(null));
+            statement.setLong(4, recipientId.id());
             statement.executeUpdate();
         }
     }
@@ -861,9 +800,10 @@ public class RecipientStore implements RecipientIdCreator, RecipientResolver, Re
             final Connection connection, final String number
     ) throws SQLException {
         final var sql = """
-                        SELECT r._id, r.number, r.uuid
+                        SELECT r._id, r.number, r.uuid, r.pni
                         FROM %s r
                         WHERE r.number = ?
+                        LIMIT 1
                         """.formatted(TABLE_RECIPIENT);
         try (final var statement = connection.prepareStatement(sql)) {
             statement.setString(1, number);
@@ -875,9 +815,10 @@ public class RecipientStore implements RecipientIdCreator, RecipientResolver, Re
             final Connection connection, final ServiceId serviceId
     ) throws SQLException {
         final var sql = """
-                        SELECT r._id, r.number, r.uuid
+                        SELECT r._id, r.number, r.uuid, r.pni
                         FROM %s r
-                        WHERE r.uuid = ?
+                        WHERE r.uuid = ? OR r.pni = ?
+                        LIMIT 1
                         """.formatted(TABLE_RECIPIENT);
         try (final var statement = connection.prepareStatement(sql)) {
             statement.setBytes(1, UuidUtil.toByteArray(serviceId.uuid()));
@@ -885,6 +826,25 @@ public class RecipientStore implements RecipientIdCreator, RecipientResolver, Re
         }
     }
 
+    private Set<RecipientWithAddress> findAllByAddress(
+            final Connection connection, final RecipientAddress address
+    ) throws SQLException {
+        final var sql = """
+                        SELECT r._id, r.number, r.uuid, r.pni
+                        FROM %s r
+                        WHERE r.uuid = ?1 OR r.pni = ?1 OR
+                              r.uuid = ?2 OR r.pni = ?2 OR
+                              r.number = ?3
+                        """.formatted(TABLE_RECIPIENT);
+        try (final var statement = connection.prepareStatement(sql)) {
+            statement.setBytes(1, address.serviceId().map(ServiceId::uuid).map(UuidUtil::toByteArray).orElse(null));
+            statement.setBytes(2, address.pni().map(ServiceId::uuid).map(UuidUtil::toByteArray).orElse(null));
+            statement.setString(3, address.number().orElse(null));
+            return Utils.executeQueryForStream(statement, this::getRecipientWithAddressFromResultSet)
+                    .collect(Collectors.toSet());
+        }
+    }
+
     private Contact getContact(final Connection connection, final RecipientId recipientId) throws SQLException {
         final var sql = (
                 """
@@ -946,8 +906,9 @@ public class RecipientStore implements RecipientIdCreator, RecipientResolver, Re
 
     private RecipientAddress getRecipientAddressFromResultSet(ResultSet resultSet) throws SQLException {
         final var serviceId = Optional.ofNullable(resultSet.getBytes("uuid")).map(ServiceId::parseOrNull);
+        final var pni = Optional.ofNullable(resultSet.getBytes("pni")).map(PNI::parseOrNull);
         final var number = Optional.ofNullable(resultSet.getString("number"));
-        return new RecipientAddress(serviceId, Optional.empty(), number);
+        return new RecipientAddress(serviceId, pni, number);
     }
 
     private RecipientId getRecipientIdFromResultSet(ResultSet resultSet) throws SQLException {
@@ -1032,5 +993,34 @@ public class RecipientStore implements RecipientIdCreator, RecipientResolver, Re
         ) throws SQLException;
     }
 
-    private record RecipientWithAddress(RecipientId id, RecipientAddress address) {}
+    private class HelperStore implements MergeRecipientHelper.Store {
+
+        private final Connection connection;
+
+        public HelperStore(final Connection connection) {
+            this.connection = connection;
+        }
+
+        @Override
+        public Set<RecipientWithAddress> findAllByAddress(final RecipientAddress address) throws SQLException {
+            return RecipientStore.this.findAllByAddress(connection, address);
+        }
+
+        @Override
+        public RecipientId addNewRecipient(final RecipientAddress address) throws SQLException {
+            return RecipientStore.this.addNewRecipient(connection, address);
+        }
+
+        @Override
+        public void updateRecipientAddress(
+                final RecipientId recipientId, final RecipientAddress address
+        ) throws SQLException {
+            RecipientStore.this.updateRecipientAddress(connection, recipientId, address);
+        }
+
+        @Override
+        public void removeRecipientAddress(final RecipientId recipientId) throws SQLException {
+            RecipientStore.this.removeRecipientAddress(connection, recipientId);
+        }
+    }
 }
diff --git a/lib/src/main/java/org/asamk/signal/manager/storage/recipients/RecipientWithAddress.java b/lib/src/main/java/org/asamk/signal/manager/storage/recipients/RecipientWithAddress.java
new file mode 100644
index 00000000..6885a8af
--- /dev/null
+++ b/lib/src/main/java/org/asamk/signal/manager/storage/recipients/RecipientWithAddress.java
@@ -0,0 +1,3 @@
+package org.asamk.signal.manager.storage.recipients;
+
+record RecipientWithAddress(RecipientId id, RecipientAddress address) {}
diff --git a/lib/src/test/java/org/asamk/signal/manager/storage/recipients/MergeRecipientHelperTest.java b/lib/src/test/java/org/asamk/signal/manager/storage/recipients/MergeRecipientHelperTest.java
new file mode 100644
index 00000000..42a57d35
--- /dev/null
+++ b/lib/src/test/java/org/asamk/signal/manager/storage/recipients/MergeRecipientHelperTest.java
@@ -0,0 +1,330 @@
+package org.asamk.signal.manager.storage.recipients;
+
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+import org.whispersystems.signalservice.api.push.PNI;
+import org.whispersystems.signalservice.api.push.ServiceId;
+
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.UUID;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+class MergeRecipientHelperTest {
+
+    static final ServiceId SERVICE_ID_A = ServiceId.from(UUID.randomUUID());
+    static final ServiceId SERVICE_ID_B = ServiceId.from(UUID.randomUUID());
+    static final ServiceId SERVICE_ID_C = ServiceId.from(UUID.randomUUID());
+    static final PNI PNI_A = PNI.from(UUID.randomUUID());
+    static final PNI PNI_B = PNI.from(UUID.randomUUID());
+    static final PNI PNI_C = PNI.from(UUID.randomUUID());
+    static final String NUMBER_A = "+AAA";
+    static final String NUMBER_B = "+BBB";
+    static final String NUMBER_C = "+CCC";
+
+    static final PartialAddresses ADDR_A = new PartialAddresses(SERVICE_ID_A, PNI_A, NUMBER_A);
+    static final PartialAddresses ADDR_B = new PartialAddresses(SERVICE_ID_B, PNI_B, NUMBER_B);
+
+    static T[] testInstancesNone = new T[]{
+            // 1
+            new T(Set.of(), ADDR_A.FULL, Set.of(rec(1000000, ADDR_A.FULL))),
+            new T(Set.of(), ADDR_A.ACI_NUM, Set.of(rec(1000000, ADDR_A.ACI_NUM))),
+            new T(Set.of(), ADDR_A.ACI_PNI, Set.of(rec(1000000, ADDR_A.ACI_PNI))),
+            new T(Set.of(), ADDR_A.PNI_S_NUM, Set.of(rec(1000000, ADDR_A.PNI_S_NUM))),
+            new T(Set.of(), ADDR_A.PNI_NUM, Set.of(rec(1000000, ADDR_A.PNI_NUM))),
+    };
+
+    static T[] testInstancesSingle = new T[]{
+            // 1
+            new T(Set.of(rec(1, ADDR_A.FULL)), ADDR_A.FULL, Set.of(rec(1, ADDR_A.FULL))),
+            new T(Set.of(rec(1, ADDR_A.ACI)), ADDR_A.FULL, Set.of(rec(1, ADDR_A.FULL))),
+            new T(Set.of(rec(1, ADDR_A.PNI)), ADDR_A.FULL, Set.of(rec(1, ADDR_A.FULL))),
+            new T(Set.of(rec(1, ADDR_A.PNI_S)), ADDR_A.FULL, Set.of(rec(1, ADDR_A.FULL))),
+            new T(Set.of(rec(1, ADDR_A.NUM)), ADDR_A.FULL, Set.of(rec(1, ADDR_A.FULL))),
+            new T(Set.of(rec(1, ADDR_A.ACI_NUM)), ADDR_A.FULL, Set.of(rec(1, ADDR_A.FULL))),
+            new T(Set.of(rec(1, ADDR_A.PNI_NUM)), ADDR_A.FULL, Set.of(rec(1, ADDR_A.FULL))),
+            new T(Set.of(rec(1, ADDR_A.PNI_S_NUM)), ADDR_A.FULL, Set.of(rec(1, ADDR_A.FULL))),
+            new T(Set.of(rec(1, ADDR_A.ACI_PNI)), ADDR_A.FULL, Set.of(rec(1, ADDR_A.FULL))),
+
+            // 10
+            new T(Set.of(rec(1, ADDR_A.FULL)), ADDR_A.ACI_NUM, Set.of(rec(1, ADDR_A.FULL))),
+            new T(Set.of(rec(1, ADDR_A.ACI)), ADDR_A.ACI_NUM, Set.of(rec(1, ADDR_A.ACI_NUM))),
+            new T(Set.of(rec(1, ADDR_A.PNI)), ADDR_A.ACI_NUM, Set.of(rec(1, ADDR_A.PNI), rec(1000000, ADDR_A.ACI_NUM))),
+            new T(Set.of(rec(1, ADDR_A.PNI_S)),
+                    ADDR_A.ACI_NUM,
+                    Set.of(rec(1, ADDR_A.PNI_S), rec(1000000, ADDR_A.ACI_NUM))),
+            new T(Set.of(rec(1, ADDR_A.NUM)), ADDR_A.ACI_NUM, Set.of(rec(1, ADDR_A.ACI_NUM))),
+            new T(Set.of(rec(1, ADDR_A.ACI_NUM)), ADDR_A.ACI_NUM, Set.of(rec(1, ADDR_A.ACI_NUM))),
+            new T(Set.of(rec(1, ADDR_A.PNI_NUM)),
+                    ADDR_A.ACI_NUM,
+                    Set.of(rec(1, ADDR_A.PNI), rec(1000000, ADDR_A.ACI_NUM))),
+            new T(Set.of(rec(1, ADDR_A.PNI_S_NUM)),
+                    ADDR_A.ACI_NUM,
+                    Set.of(rec(1, ADDR_A.PNI_S), rec(1000000, ADDR_A.ACI_NUM))),
+            new T(Set.of(rec(1, ADDR_A.ACI_PNI)), ADDR_A.ACI_NUM, Set.of(rec(1, ADDR_A.FULL))),
+
+            // 19
+            new T(Set.of(rec(1, ADDR_A.FULL)), ADDR_A.PNI_NUM, Set.of(rec(1, ADDR_A.FULL))),
+            new T(Set.of(rec(1, ADDR_A.ACI)), ADDR_A.PNI_NUM, Set.of(rec(1, ADDR_A.ACI), rec(1000000, ADDR_A.PNI_NUM))),
+            new T(Set.of(rec(1, ADDR_A.PNI)), ADDR_A.PNI_NUM, Set.of(rec(1, ADDR_A.PNI_NUM))),
+            new T(Set.of(rec(1, ADDR_A.PNI_S)), ADDR_A.PNI_NUM, Set.of(rec(1, ADDR_A.PNI_NUM))),
+            new T(Set.of(rec(1, ADDR_A.NUM)), ADDR_A.PNI_NUM, Set.of(rec(1, ADDR_A.PNI_NUM))),
+            new T(Set.of(rec(1, ADDR_A.ACI_NUM)),
+                    ADDR_A.PNI_NUM,
+                    Set.of(rec(1, ADDR_A.ACI), rec(1000000, ADDR_A.PNI_NUM))),
+            new T(Set.of(rec(1, ADDR_A.PNI_NUM)), ADDR_A.PNI_NUM, Set.of(rec(1, ADDR_A.PNI_NUM))),
+            new T(Set.of(rec(1, ADDR_A.PNI_S_NUM)), ADDR_A.PNI_NUM, Set.of(rec(1, ADDR_A.PNI_NUM))),
+            new T(Set.of(rec(1, ADDR_A.ACI_PNI)), ADDR_A.PNI_NUM, Set.of(rec(1, ADDR_A.FULL))),
+
+            // 28
+            new T(Set.of(rec(1, ADDR_A.FULL)), ADDR_A.PNI_S_NUM, Set.of(rec(1, ADDR_A.FULL))),
+            new T(Set.of(rec(1, ADDR_A.ACI)),
+                    ADDR_A.PNI_S_NUM,
+                    Set.of(rec(1, ADDR_A.ACI), rec(1000000, ADDR_A.PNI_S_NUM))),
+            new T(Set.of(rec(1, ADDR_A.PNI)), ADDR_A.PNI_S_NUM, Set.of(rec(1, ADDR_A.PNI_NUM))),
+            new T(Set.of(rec(1, ADDR_A.PNI_S)), ADDR_A.PNI_S_NUM, Set.of(rec(1, ADDR_A.PNI_S_NUM))),
+            new T(Set.of(rec(1, ADDR_A.NUM)), ADDR_A.PNI_S_NUM, Set.of(rec(1, ADDR_A.PNI_S_NUM))),
+            new T(Set.of(rec(1, ADDR_A.ACI_NUM)),
+                    ADDR_A.PNI_S_NUM,
+                    Set.of(rec(1, ADDR_A.ACI), rec(1000000, ADDR_A.PNI_S_NUM))),
+            new T(Set.of(rec(1, ADDR_A.PNI_NUM)), ADDR_A.PNI_S_NUM, Set.of(rec(1, ADDR_A.PNI_NUM))),
+            new T(Set.of(rec(1, ADDR_A.PNI_S_NUM)), ADDR_A.PNI_S_NUM, Set.of(rec(1, ADDR_A.PNI_S_NUM))),
+            new T(Set.of(rec(1, ADDR_A.ACI_PNI)), ADDR_A.PNI_S_NUM, Set.of(rec(1, ADDR_A.FULL))),
+
+            // 37
+            new T(Set.of(rec(1, ADDR_A.FULL)), ADDR_A.ACI_PNI, Set.of(rec(1, ADDR_A.FULL))),
+            new T(Set.of(rec(1, ADDR_A.ACI)), ADDR_A.ACI_PNI, Set.of(rec(1, ADDR_A.ACI_PNI))),
+            new T(Set.of(rec(1, ADDR_A.PNI)), ADDR_A.ACI_PNI, Set.of(rec(1, ADDR_A.ACI_PNI))),
+            new T(Set.of(rec(1, ADDR_A.PNI_S)), ADDR_A.ACI_PNI, Set.of(rec(1, ADDR_A.ACI_PNI))),
+            new T(Set.of(rec(1, ADDR_A.NUM)), ADDR_A.ACI_PNI, Set.of(rec(1, ADDR_A.NUM), rec(1000000, ADDR_A.ACI_PNI))),
+            new T(Set.of(rec(1, ADDR_A.ACI_NUM)), ADDR_A.ACI_PNI, Set.of(rec(1, ADDR_A.FULL))),
+            new T(Set.of(rec(1, ADDR_A.PNI_NUM)), ADDR_A.ACI_PNI, Set.of(rec(1, ADDR_A.FULL))),
+            new T(Set.of(rec(1, ADDR_A.PNI_S_NUM)), ADDR_A.ACI_PNI, Set.of(rec(1, ADDR_A.FULL))),
+            new T(Set.of(rec(1, ADDR_A.ACI_PNI)), ADDR_A.ACI_PNI, Set.of(rec(1, ADDR_A.ACI_PNI))),
+
+            new T(Set.of(rec(1, ADDR_A.FULL)), ADDR_B.FULL, Set.of(rec(1, ADDR_A.FULL), rec(1000000, ADDR_B.FULL))),
+    };
+
+    static T[] testInstancesTwo = new T[]{
+            // 1
+            new T(Set.of(rec(1, ADDR_A.ACI), rec(2, ADDR_A.PNI)), ADDR_A.FULL, Set.of(rec(1, ADDR_A.FULL))),
+            new T(Set.of(rec(1, ADDR_A.ACI), rec(2, ADDR_A.PNI_S)), ADDR_A.FULL, Set.of(rec(1, ADDR_A.FULL))),
+            new T(Set.of(rec(1, ADDR_A.ACI), rec(2, ADDR_A.NUM)), ADDR_A.FULL, Set.of(rec(1, ADDR_A.FULL))),
+            new T(Set.of(rec(1, ADDR_A.ACI), rec(2, ADDR_A.PNI_NUM)), ADDR_A.FULL, Set.of(rec(1, ADDR_A.FULL))),
+            new T(Set.of(rec(1, ADDR_A.ACI), rec(2, ADDR_A.PNI_S_NUM)), ADDR_A.FULL, Set.of(rec(1, ADDR_A.FULL))),
+            new T(Set.of(rec(1, ADDR_A.PNI), rec(2, ADDR_A.NUM)), ADDR_A.FULL, Set.of(rec(1, ADDR_A.FULL))),
+            new T(Set.of(rec(1, ADDR_A.PNI), rec(2, ADDR_A.ACI_NUM)), ADDR_A.FULL, Set.of(rec(2, ADDR_A.FULL))),
+            new T(Set.of(rec(1, ADDR_A.PNI_S), rec(2, ADDR_A.NUM)), ADDR_A.FULL, Set.of(rec(1, ADDR_A.FULL))),
+            new T(Set.of(rec(1, ADDR_A.PNI_S), rec(2, ADDR_A.ACI_NUM)), ADDR_A.FULL, Set.of(rec(2, ADDR_A.FULL))),
+            new T(Set.of(rec(1, ADDR_A.NUM), rec(2, ADDR_A.PNI_S)), ADDR_A.FULL, Set.of(rec(2, ADDR_A.FULL))),
+            new T(Set.of(rec(1, ADDR_A.NUM), rec(2, ADDR_A.ACI_PNI)), ADDR_A.FULL, Set.of(rec(2, ADDR_A.FULL))),
+
+            // 12
+            new T(Set.of(rec(1, ADDR_A.ACI), rec(2, ADDR_A.NUM)), ADDR_A.ACI_NUM, Set.of(rec(1, ADDR_A.ACI_NUM))),
+            new T(Set.of(rec(1, ADDR_A.ACI), rec(2, ADDR_A.PNI_NUM)), ADDR_A.ACI_NUM, Set.of(rec(1, ADDR_A.FULL))),
+            new T(Set.of(rec(1, ADDR_A.ACI), rec(2, ADDR_A.PNI_S_NUM)),
+                    ADDR_A.ACI_NUM,
+                    Set.of(rec(1, ADDR_A.ACI_NUM), rec(2, ADDR_A.PNI_S))),
+            new T(Set.of(rec(1, ADDR_A.NUM), rec(2, ADDR_A.ACI_PNI)), ADDR_A.ACI_NUM, Set.of(rec(2, ADDR_A.FULL))),
+
+            // 16
+            new T(Set.of(rec(1, ADDR_A.ACI), rec(2, ADDR_A.PNI_NUM)),
+                    ADDR_A.PNI_NUM,
+                    Set.of(rec(1, ADDR_A.ACI), rec(2, ADDR_A.PNI_NUM))),
+            new T(Set.of(rec(1, ADDR_A.ACI), rec(2, ADDR_A.PNI_S_NUM)),
+                    ADDR_A.PNI_NUM,
+                    Set.of(rec(1, ADDR_A.ACI), rec(2, ADDR_A.PNI_NUM))),
+            new T(Set.of(rec(1, ADDR_A.PNI), rec(2, ADDR_A.NUM)), ADDR_A.PNI_NUM, Set.of(rec(1, ADDR_A.PNI_NUM))),
+            new T(Set.of(rec(1, ADDR_A.PNI), rec(2, ADDR_A.ACI_NUM)),
+                    ADDR_A.PNI_NUM,
+                    Set.of(rec(1, ADDR_A.PNI_NUM), rec(2, ADDR_A.ACI))),
+            new T(Set.of(rec(1, ADDR_A.PNI_S), rec(2, ADDR_A.NUM)), ADDR_A.PNI_NUM, Set.of(rec(1, ADDR_A.PNI_NUM))),
+            new T(Set.of(rec(1, ADDR_A.PNI_S), rec(2, ADDR_A.ACI_NUM)),
+                    ADDR_A.PNI_NUM,
+                    Set.of(rec(1, ADDR_A.PNI_NUM), rec(2, ADDR_A.ACI))),
+            new T(Set.of(rec(1, ADDR_A.NUM), rec(2, ADDR_A.PNI_S)), ADDR_A.PNI_NUM, Set.of(rec(2, ADDR_A.PNI_NUM))),
+            new T(Set.of(rec(1, ADDR_A.NUM), rec(2, ADDR_A.ACI_PNI)), ADDR_A.PNI_NUM, Set.of(rec(2, ADDR_A.FULL))),
+
+            // 24
+            new T(Set.of(rec(1, ADDR_A.ACI), rec(2, ADDR_A.PNI_NUM)),
+                    ADDR_A.PNI_S_NUM,
+                    Set.of(rec(1, ADDR_A.ACI), rec(2, ADDR_A.PNI_NUM))),
+            new T(Set.of(rec(1, ADDR_A.ACI), rec(2, ADDR_A.PNI_S_NUM)),
+                    ADDR_A.PNI_S_NUM,
+                    Set.of(rec(1, ADDR_A.ACI), rec(2, ADDR_A.PNI_S_NUM))),
+            new T(Set.of(rec(1, ADDR_A.PNI), rec(2, ADDR_A.NUM)), ADDR_A.PNI_S_NUM, Set.of(rec(1, ADDR_A.PNI_NUM))),
+            new T(Set.of(rec(1, ADDR_A.PNI), rec(2, ADDR_A.ACI_NUM)),
+                    ADDR_A.PNI_S_NUM,
+                    Set.of(rec(1, ADDR_A.PNI_NUM), rec(2, ADDR_A.ACI))),
+            new T(Set.of(rec(1, ADDR_A.PNI_S), rec(2, ADDR_A.NUM)), ADDR_A.PNI_S_NUM, Set.of(rec(1, ADDR_A.PNI_S_NUM))),
+            new T(Set.of(rec(1, ADDR_A.PNI_S), rec(2, ADDR_A.ACI_NUM)),
+                    ADDR_A.PNI_S_NUM,
+                    Set.of(rec(1, ADDR_A.PNI_S_NUM), rec(2, ADDR_A.ACI))),
+            new T(Set.of(rec(1, ADDR_A.NUM), rec(2, ADDR_A.PNI_S)), ADDR_A.PNI_S_NUM, Set.of(rec(2, ADDR_A.PNI_S_NUM))),
+            new T(Set.of(rec(1, ADDR_A.NUM), rec(2, ADDR_A.ACI_PNI)), ADDR_A.PNI_S_NUM, Set.of(rec(2, ADDR_A.FULL))),
+
+            // 32
+            new T(Set.of(rec(1, ADDR_A.ACI), rec(2, ADDR_A.PNI)), ADDR_A.ACI_PNI, Set.of(rec(1, ADDR_A.ACI_PNI))),
+            new T(Set.of(rec(1, ADDR_A.ACI), rec(2, ADDR_A.PNI_S)), ADDR_A.ACI_PNI, Set.of(rec(1, ADDR_A.ACI_PNI))),
+            new T(Set.of(rec(1, ADDR_A.ACI), rec(2, ADDR_A.PNI_NUM)), ADDR_A.ACI_PNI, Set.of(rec(1, ADDR_A.FULL))),
+            new T(Set.of(rec(1, ADDR_A.ACI), rec(2, ADDR_A.PNI_S_NUM)),
+                    ADDR_A.ACI_PNI,
+                    Set.of(rec(1, ADDR_A.ACI_PNI), rec(2, ADDR_A.NUM))),
+            new T(Set.of(rec(1, ADDR_A.PNI), rec(2, ADDR_A.ACI_NUM)), ADDR_A.ACI_PNI, Set.of(rec(2, ADDR_A.FULL))),
+            new T(Set.of(rec(1, ADDR_A.PNI_S), rec(2, ADDR_A.ACI_NUM)), ADDR_A.ACI_PNI, Set.of(rec(2, ADDR_A.FULL))),
+    };
+
+    static T[] testInstancesThree = new T[]{
+            // 1
+            new T(Set.of(rec(1, ADDR_A.ACI), rec(2, ADDR_A.PNI), rec(3, ADDR_A.NUM)),
+                    ADDR_A.FULL,
+                    Set.of(rec(1, ADDR_A.FULL))),
+            new T(Set.of(rec(1, ADDR_A.ACI.withIdentifiersFrom(ADDR_B.PNI)), rec(2, ADDR_A.PNI), rec(3, ADDR_A.NUM)),
+                    ADDR_A.FULL,
+                    Set.of(rec(1, ADDR_A.FULL))),
+            new T(Set.of(rec(1, ADDR_A.ACI.withIdentifiersFrom(ADDR_B.NUM)), rec(2, ADDR_A.PNI), rec(3, ADDR_A.NUM)),
+                    ADDR_A.FULL,
+                    Set.of(rec(1, ADDR_A.FULL))),
+            new T(Set.of(rec(1, ADDR_A.ACI), rec(2, ADDR_A.PNI), rec(3, ADDR_A.NUM.withIdentifiersFrom(ADDR_B.ACI))),
+                    ADDR_A.FULL,
+                    Set.of(rec(1, ADDR_A.FULL), rec(3, ADDR_B.ACI))),
+            new T(Set.of(rec(1, ADDR_A.ACI), rec(2, ADDR_A.PNI.withIdentifiersFrom(ADDR_B.ACI)), rec(3, ADDR_A.NUM)),
+                    ADDR_A.FULL,
+                    Set.of(rec(1, ADDR_A.FULL), rec(2, ADDR_B.ACI))),
+    };
+
+    @ParameterizedTest
+    @MethodSource
+    void resolveRecipientTrustedLocked_NoneExisting(T test) throws Exception {
+        final var testStore = new TestStore(test.input);
+        MergeRecipientHelper.resolveRecipientTrustedLocked(testStore, test.request);
+        assertEquals(test.output, testStore.getRecipients());
+    }
+
+    private static Stream<Arguments> resolveRecipientTrustedLocked_NoneExisting() {
+        return Arrays.stream(testInstancesNone).map(Arguments::of);
+    }
+
+    @ParameterizedTest
+    @MethodSource
+    void resolveRecipientTrustedLocked_SingleExisting(T test) throws Exception {
+        final var testStore = new TestStore(test.input);
+        MergeRecipientHelper.resolveRecipientTrustedLocked(testStore, test.request);
+        assertEquals(test.output, testStore.getRecipients());
+    }
+
+    private static Stream<Arguments> resolveRecipientTrustedLocked_SingleExisting() {
+        return Arrays.stream(testInstancesSingle).map(Arguments::of);
+    }
+
+    @ParameterizedTest
+    @MethodSource
+    void resolveRecipientTrustedLocked_TwoExisting(T test) throws Exception {
+        final var testStore = new TestStore(test.input);
+        MergeRecipientHelper.resolveRecipientTrustedLocked(testStore, test.request);
+        assertEquals(test.output, testStore.getRecipients());
+    }
+
+    private static Stream<Arguments> resolveRecipientTrustedLocked_TwoExisting() {
+        return Arrays.stream(testInstancesTwo).map(Arguments::of);
+    }
+
+    @ParameterizedTest
+    @MethodSource
+    void resolveRecipientTrustedLocked_ThreeExisting(T test) throws Exception {
+        final var testStore = new TestStore(test.input);
+        MergeRecipientHelper.resolveRecipientTrustedLocked(testStore, test.request);
+        assertEquals(test.output, testStore.getRecipients());
+    }
+
+    private static Stream<Arguments> resolveRecipientTrustedLocked_ThreeExisting() {
+        return Arrays.stream(testInstancesThree).map(Arguments::of);
+    }
+
+    private static RecipientWithAddress rec(long recipientId, RecipientAddress address) {
+        return new RecipientWithAddress(new RecipientId(recipientId, null), address);
+    }
+
+    record T(
+            Set<RecipientWithAddress> input, RecipientAddress request, Set<RecipientWithAddress> output
+    ) {
+
+        @Override
+        public String toString() {
+            return "T{#input=%s, request=%s_%s_%s, #output=%s}".formatted(input.size(),
+                    request.serviceId().isPresent() ? "SVI" : "",
+                    request.pni().isPresent() ? "PNI" : "",
+                    request.number().isPresent() ? "NUM" : "",
+                    output.size());
+        }
+    }
+
+    static class TestStore implements MergeRecipientHelper.Store {
+
+        final Set<RecipientWithAddress> recipients;
+        long nextRecipientId = 1000000;
+
+        TestStore(final Set<RecipientWithAddress> recipients) {
+            this.recipients = new HashSet<>(recipients);
+        }
+
+        public Set<RecipientWithAddress> getRecipients() {
+            return recipients;
+        }
+
+        @Override
+        public Set<RecipientWithAddress> findAllByAddress(final RecipientAddress address) {
+            return recipients.stream().filter(r -> r.address().matches(address)).collect(Collectors.toSet());
+        }
+
+        @Override
+        public RecipientId addNewRecipient(final RecipientAddress address) {
+            final var recipientId = new RecipientId(nextRecipientId++, null);
+            recipients.add(new RecipientWithAddress(recipientId, address));
+            return recipientId;
+        }
+
+        @Override
+        public void updateRecipientAddress(
+                final RecipientId recipientId, final RecipientAddress address
+        ) {
+            recipients.removeIf(r -> r.id().equals(recipientId));
+            recipients.add(new RecipientWithAddress(recipientId, address));
+        }
+
+        @Override
+        public void removeRecipientAddress(final RecipientId recipientId) {
+            recipients.removeIf(r -> r.id().equals(recipientId));
+        }
+    }
+
+    private record PartialAddresses(
+            RecipientAddress FULL,
+            RecipientAddress ACI,
+            RecipientAddress PNI,
+            RecipientAddress PNI_S,
+            RecipientAddress NUM,
+            RecipientAddress ACI_NUM,
+            RecipientAddress PNI_NUM,
+            RecipientAddress PNI_S_NUM,
+            RecipientAddress ACI_PNI
+    ) {
+
+        PartialAddresses(ServiceId serviceId, PNI pni, String number) {
+            this(new RecipientAddress(serviceId, pni, number),
+                    new RecipientAddress(serviceId, null, null),
+                    new RecipientAddress(null, pni, null),
+                    new RecipientAddress(ServiceId.from(pni.uuid()), null, null),
+                    new RecipientAddress(null, null, number),
+                    new RecipientAddress(serviceId, null, number),
+                    new RecipientAddress(null, pni, number),
+                    new RecipientAddress(ServiceId.from(pni.uuid()), null, number),
+                    new RecipientAddress(serviceId, pni, null));
+        }
+    }
+}