diff --git a/ts/ConversationController.ts b/ts/ConversationController.ts
index d99ae22c1c7c..ebc7239c1bd8 100644
--- a/ts/ConversationController.ts
+++ b/ts/ConversationController.ts
@@ -470,17 +470,20 @@ export class ConversationController {
   } {
     const dataProvided = [];
     if (providedAci) {
-      dataProvided.push('aci');
+      dataProvided.push(`aci=${providedAci}`);
     }
     if (e164) {
-      dataProvided.push('e164');
+      dataProvided.push(`e164=${e164}`);
     }
     if (providedPni) {
-      dataProvided.push('pni');
+      dataProvided.push(`pni=${providedPni}`);
     }
-    const logId = `maybeMergeContacts/${reason}/${dataProvided.join('+')}`;
+    const logId = `maybeMergeContacts/${reason}/${dataProvided.join(',')}`;
 
-    const aci = providedAci ? UUID.cast(providedAci) : undefined;
+    const aci =
+      providedAci && providedAci !== providedPni
+        ? UUID.cast(providedAci)
+        : undefined;
     const pni = providedPni ? UUID.cast(providedPni) : undefined;
     const mergePromises: Array<Promise<void>> = [];
 
@@ -517,7 +520,8 @@ export class ConversationController {
       if (!match) {
         if (targetConversation) {
           log.info(
-            `${logId}: No match for ${key}, applying to target conversation`
+            `${logId}: No match for ${key}, applying to target ` +
+              `conversation - ${targetConversation.idForLogging()}`
           );
           // Note: This line might erase a known e164 or PNI
           applyChangeToConversation(targetConversation, {
@@ -609,7 +613,8 @@ export class ConversationController {
         // Clear the value on the current match, since it belongs on targetConversation!
         //   Note: we need to do the remove first, because it will clear the lookup!
         log.info(
-          `${logId}: Clearing ${key} on match, and adding it to target conversation`
+          `${logId}: Clearing ${key} on match, and adding it to target ` +
+            `conversation - ${targetConversation.idForLogging()}`
         );
         const change: Pick<
           Partial<ConversationAttributesType>,
@@ -635,7 +640,7 @@ export class ConversationController {
         if (willMerge) {
           log.warn(
             `${logId}: Removing old conversation which matched on ${key}. ` +
-              'Merging with target conversation.'
+              `Merging with target conversation - ${targetConversation.idForLogging()}`
           );
           mergePromises.push(
             mergeOldAndNew({
@@ -649,7 +654,10 @@ export class ConversationController {
         }
       } else if (targetConversation && !targetConversation?.get(key)) {
         // This is mostly for the situation where PNI was erased when updating e164
-        log.debug(`${logId}: Re-adding ${key} on target conversation`);
+        log.debug(
+          `${logId}: Re-adding ${key} on target conversation - ` +
+            `${targetConversation.idForLogging()}`
+        );
         applyChangeToConversation(targetConversation, {
           [key]: value,
         });
@@ -1075,6 +1083,8 @@ export class ConversationController {
 
     // Note: we explicitly don't want to update V2 groups
 
+    const obsoleteHadMessages = (obsolete.get('messageCount') ?? 0) > 0;
+
     log.warn(`${logId}: Delete the obsolete conversation from the database`);
     await removeConversation(obsoleteId);
 
@@ -1112,7 +1122,12 @@ export class ConversationController {
     const titleIsUseful = Boolean(
       obsoleteTitleInfo && getTitleNoDefault(obsoleteTitleInfo)
     );
-    if (obsoleteTitleInfo && titleIsUseful && !fromPniSignature) {
+    if (
+      obsoleteTitleInfo &&
+      titleIsUseful &&
+      !fromPniSignature &&
+      obsoleteHadMessages
+    ) {
       drop(current.addConversationMerge(obsoleteTitleInfo));
     }
 
diff --git a/ts/test-electron/ConversationController_test.ts b/ts/test-electron/ConversationController_test.ts
index f6c9f59074ee..b1dcdc82e84c 100644
--- a/ts/test-electron/ConversationController_test.ts
+++ b/ts/test-electron/ConversationController_test.ts
@@ -571,6 +571,28 @@ describe('ConversationController', () => {
 
         assert.strictEqual(result?.id, initial?.id, 'result and initial match');
       });
+      it('adds PNI to conversation with e164+ACI', () => {
+        const initial = create('initial', {
+          aci: ACI_1,
+          e164: E164_1,
+        });
+
+        const { conversation: result } =
+          window.ConversationController.maybeMergeContacts({
+            mergeOldAndNew,
+            aci: PNI_1,
+            pni: PNI_1,
+            e164: E164_1,
+            reason,
+          });
+        expectPropsAndLookups(result, 'result', {
+          uuid: ACI_1,
+          e164: E164_1,
+          pni: PNI_1,
+        });
+
+        assert.strictEqual(result?.id, initial?.id, 'result and initial match');
+      });
       it('replaces PNI in conversation with all data', () => {
         const initial = create('initial', {
           aci: ACI_1,
diff --git a/ts/test-mock/pnp/merge_test.ts b/ts/test-mock/pnp/merge_test.ts
index f1a78f3be87f..672ef0428959 100644
--- a/ts/test-mock/pnp/merge_test.ts
+++ b/ts/test-mock/pnp/merge_test.ts
@@ -101,123 +101,140 @@ describe('pnp/merge', function needsName() {
   });
 
   for (const finalContact of [UUIDKind.ACI, UUIDKind.PNI]) {
-    // eslint-disable-next-line no-loop-func
-    it(`happens via storage service, with notification (${finalContact})`, async () => {
-      const { phone } = bootstrap;
+    for (const withNotification of [false, true]) {
+      const testName =
+        'happens via storage service, ' +
+        `${withNotification ? 'with' : 'without'} notification ` +
+        `(${finalContact})`;
 
-      const window = await app.getWindow();
-      const leftPane = window.locator('.left-pane-wrapper');
+      // eslint-disable-next-line no-loop-func
+      it(testName, async () => {
+        const { phone } = bootstrap;
 
-      debug('opening conversation with the aci contact');
-      await leftPane
-        .locator(`[data-testid="${pniContact.device.uuid}"]`)
-        .click();
+        const window = await app.getWindow();
+        const leftPane = window.locator('.left-pane-wrapper');
 
-      await window.locator('.module-conversation-hero').waitFor();
-
-      debug('Send message to ACI');
-      {
-        const composeArea = window.locator(
-          '.composition-area-wrapper, .conversation .ConversationView'
-        );
-        const compositionInput = composeArea.locator(
-          '[data-testid=CompositionInput]'
-        );
-
-        await compositionInput.type('Hello ACI');
-        await compositionInput.press('Enter');
-      }
-
-      debug('opening conversation with the pni contact');
-      await leftPane
-        .locator('.module-conversation-list__item--contact-or-conversation')
-        .first()
-        .click();
-
-      await window.locator('.module-conversation-hero').waitFor();
-
-      debug('Verify starting state');
-      {
-        // No messages
-        const messages = window.locator('.module-message__text');
-        assert.strictEqual(await messages.count(), 0, 'message count');
-
-        // No notifications
-        const notifications = window.locator('.SystemMessage');
-        assert.strictEqual(
-          await notifications.count(),
-          0,
-          'notification count'
-        );
-      }
-
-      debug('Send message to PNI');
-      {
-        const composeArea = window.locator(
-          '.composition-area-wrapper, .conversation .ConversationView'
-        );
-        const compositionInput = composeArea.locator(
-          '[data-testid=CompositionInput]'
-        );
-
-        await compositionInput.type('Hello PNI');
-        await compositionInput.press('Enter');
-      }
-
-      if (finalContact === UUIDKind.ACI) {
-        debug('switching back to ACI conversation');
+        debug('opening conversation with the aci contact');
         await leftPane
           .locator(`[data-testid="${pniContact.device.uuid}"]`)
           .click();
 
         await window.locator('.module-conversation-hero').waitFor();
-      }
 
-      debug(
-        'removing both contacts from storage service, adding one combined contact'
-      );
-      {
-        const state = await phone.expectStorageState('consistency check');
-        await phone.setStorageState(
-          state.mergeContact(pniContact, {
-            identityState: Proto.ContactRecord.IdentityState.DEFAULT,
-            whitelisted: true,
-            identityKey: pniContact.publicKey.serialize(),
-            profileKey: pniContact.profileKey.serialize(),
-          })
+        debug('Send message to ACI');
+        {
+          const composeArea = window.locator(
+            '.composition-area-wrapper, .conversation .ConversationView'
+          );
+          const compositionInput = composeArea.locator(
+            '[data-testid=CompositionInput]'
+          );
+
+          await compositionInput.type('Hello ACI');
+          await compositionInput.press('Enter');
+        }
+
+        debug('opening conversation with the pni contact');
+        await leftPane
+          .locator('.module-conversation-list__item--contact-or-conversation')
+          .first()
+          .click();
+
+        await window.locator('.module-conversation-hero').waitFor();
+
+        debug('Verify starting state');
+        {
+          // No messages
+          const messages = window.locator('.module-message__text');
+          assert.strictEqual(await messages.count(), 0, 'message count');
+
+          // No notifications
+          const notifications = window.locator('.SystemMessage');
+          assert.strictEqual(
+            await notifications.count(),
+            0,
+            'notification count'
+          );
+        }
+
+        if (withNotification) {
+          debug('Send message to PNI');
+          const composeArea = window.locator(
+            '.composition-area-wrapper, .conversation .ConversationView'
+          );
+          const compositionInput = composeArea.locator(
+            '[data-testid=CompositionInput]'
+          );
+
+          await compositionInput.type('Hello PNI');
+          await compositionInput.press('Enter');
+        }
+
+        if (finalContact === UUIDKind.ACI) {
+          debug('switching back to ACI conversation');
+          await leftPane
+            .locator(`[data-testid="${pniContact.device.uuid}"]`)
+            .click();
+
+          await window.locator('.module-conversation-hero').waitFor();
+        }
+
+        debug(
+          'removing both contacts from storage service, adding one combined contact'
         );
-        await phone.sendFetchStorage({
-          timestamp: bootstrap.getTimestamp(),
-        });
-      }
+        {
+          const state = await phone.expectStorageState('consistency check');
+          await phone.setStorageState(
+            state.mergeContact(pniContact, {
+              identityState: Proto.ContactRecord.IdentityState.DEFAULT,
+              whitelisted: true,
+              identityKey: pniContact.publicKey.serialize(),
+              profileKey: pniContact.profileKey.serialize(),
+            })
+          );
+          await phone.sendFetchStorage({
+            timestamp: bootstrap.getTimestamp(),
+          });
+          await app.waitForManifestVersion(state.version);
+        }
 
-      // wait for desktop to process these changes
-      await window.locator('.SystemMessage').waitFor();
+        debug('Verify final state');
+        {
+          // Should have both PNI and ACI messages
+          await window
+            .locator('.module-message__text >> "Hello ACI"')
+            .waitFor();
+          if (withNotification) {
+            await window
+              .locator('.module-message__text >> "Hello PNI"')
+              .waitFor();
+          }
 
-      debug('Verify final state');
-      {
-        // Should have both PNI and ACI messages
-        await window.locator('.module-message__text >> "Hello ACI"').waitFor();
-        await window.locator('.module-message__text >> "Hello PNI"').waitFor();
+          const messages = window.locator('.module-message__text');
+          assert.strictEqual(
+            await messages.count(),
+            withNotification ? 2 : 1,
+            'message count'
+          );
 
-        const messages = window.locator('.module-message__text');
-        assert.strictEqual(await messages.count(), 2, 'message count');
+          // One notification - the merge
+          const notifications = window.locator('.SystemMessage');
+          assert.strictEqual(
+            await notifications.count(),
+            withNotification ? 1 : 0,
+            'notification count'
+          );
 
-        // One notification - the merge
-        const notifications = window.locator('.SystemMessage');
-        assert.strictEqual(
-          await notifications.count(),
-          1,
-          'notification count'
-        );
-
-        const first = await notifications.first();
-        assert.match(
-          await first.innerText(),
-          /Your message history with ACI Contact and their number .* has been merged./
-        );
-      }
-    });
+          if (withNotification) {
+            const first = await notifications.first();
+            assert.match(
+              await first.innerText(),
+              /Your message history with ACI Contact and their number .* has been merged./
+            );
+          }
+        }
+      });
+    }
   }
 
   it('accepts storage service contact splitting', async () => {