diff --git a/lib/handlers/user-infos-handler.react.js b/lib/handlers/user-infos-handler.react.js
--- a/lib/handlers/user-infos-handler.react.js
+++ b/lib/handlers/user-infos-handler.react.js
@@ -80,7 +80,7 @@
     }
     void (async () => {
       try {
-        await getAndUpdateDeviceListsForUsers(usersWithMissingDeviceList);
+        await getAndUpdateDeviceListsForUsers(usersWithMissingDeviceList, true);
       } catch (e) {
         console.log(
           `Error getting and setting peer device list: ${
diff --git a/lib/hooks/peer-list-hooks.js b/lib/hooks/peer-list-hooks.js
--- a/lib/hooks/peer-list-hooks.js
+++ b/lib/hooks/peer-list-hooks.js
@@ -4,19 +4,25 @@
 import * as React from 'react';
 
 import { setPeerDeviceListsActionType } from '../actions/aux-user-actions.js';
-import { getRelativeUserIDs } from '../selectors/user-selectors.js';
+import {
+  getAllPeerDevices,
+  getRelativeUserIDs,
+} from '../selectors/user-selectors.js';
 import { IdentityClientContext } from '../shared/identity-client-context.js';
 import { useTunnelbroker } from '../tunnelbroker/tunnelbroker-context.js';
 import type {
   UsersRawDeviceLists,
   UsersDevicesPlatformDetails,
   SignedDeviceList,
+  RawDeviceList,
 } from '../types/identity-service-types.js';
 import {
   type DeviceListUpdated,
   peerToPeerMessageTypes,
 } from '../types/tunnelbroker/peer-to-peer-message-types.js';
+import { getContentSigningKey } from '../utils/crypto-utils.js';
 import { convertSignedDeviceListsToRawDeviceLists } from '../utils/device-list-utils.js';
+import { values } from '../utils/objects.js';
 import { useDispatch, useSelector } from '../utils/redux-utils.js';
 
 function useCreateInitialPeerList(): () => Promise<void> {
@@ -76,11 +82,16 @@
 
 function useGetAndUpdateDeviceListsForUsers(): (
   userIDs: $ReadOnlyArray<string>,
+  broadcastUpdates: ?boolean,
 ) => Promise<void> {
   const getDeviceListsForUsers = useGetDeviceListsForUsers();
   const dispatch = useDispatch();
+  const broadcastDeviceListUpdates = useBroadcastDeviceListUpdates();
+
+  const allPeerDevices = useSelector(getAllPeerDevices);
+
   return React.useCallback(
-    async (userIDs: $ReadOnlyArray<string>) => {
+    async (userIDs: $ReadOnlyArray<string>, broadcastUpdates: ?boolean) => {
       const { deviceLists, usersPlatformDetails } =
         await getDeviceListsForUsers(userIDs);
       if (Object.keys(deviceLists).length === 0) {
@@ -90,8 +101,29 @@
         type: setPeerDeviceListsActionType,
         payload: { deviceLists, usersPlatformDetails },
       });
+
+      if (!broadcastUpdates) {
+        return;
+      }
+
+      const thisDeviceID = await getContentSigningKey();
+
+      const newDevices = values(deviceLists)
+        .map((deviceList: RawDeviceList) => deviceList.devices)
+        .flat()
+        .filter(
+          deviceID =>
+            !allPeerDevices.includes(deviceID) && deviceID !== thisDeviceID,
+        );
+
+      await broadcastDeviceListUpdates(newDevices);
     },
-    [dispatch, getDeviceListsForUsers],
+    [
+      allPeerDevices,
+      broadcastDeviceListUpdates,
+      dispatch,
+      getDeviceListsForUsers,
+    ],
   );
 }
 
diff --git a/lib/selectors/user-selectors.js b/lib/selectors/user-selectors.js
--- a/lib/selectors/user-selectors.js
+++ b/lib/selectors/user-selectors.js
@@ -28,7 +28,7 @@
   AccountUserInfo,
   CurrentUserInfo,
 } from '../types/user-types.js';
-import { entries } from '../utils/objects.js';
+import { entries, values } from '../utils/objects.js';
 
 // Used for specific message payloads that include an array of user IDs, ie.
 // array of initial users, array of added users
@@ -242,6 +242,17 @@
         .flat(),
   );
 
+const getAllPeerDevices: (state: BaseAppState<>) => $ReadOnlyArray<string> =
+  createSelector(
+    (state: BaseAppState<>) => state.auxUserStore.auxUserInfos,
+    (auxUserInfos: AuxUserInfos): $ReadOnlyArray<string> =>
+      values(auxUserInfos)
+        .map(
+          (auxUserInfo: AuxUserInfo) => auxUserInfo.deviceList?.devices ?? [],
+        )
+        .flat(),
+  );
+
 export {
   userIDsToRelativeUserInfos,
   getRelativeMemberInfos,
@@ -254,4 +265,5 @@
   getRelativeUserIDs,
   usersWithMissingDeviceListSelector,
   getForeignPeerDevices,
+  getAllPeerDevices,
 };