diff --git a/res/layout/dialog_audio_sharing_join.xml b/res/layout/dialog_audio_sharing_join.xml
new file mode 100644
index 0000000..42d964a
--- /dev/null
+++ b/res/layout/dialog_audio_sharing_join.xml
@@ -0,0 +1,53 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (C) 2023 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<LinearLayout
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:padding="24dp"
+    android:orientation="vertical">
+
+    <TextView
+        android:id="@+id/share_audio_subtitle1"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:textAlignment="center"
+        android:layout_gravity="center"/>
+
+    <TextView
+        android:id="@+id/share_audio_subtitle2"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:textAlignment="center"
+        android:layout_gravity="center"/>
+
+    <Button
+        android:id="@+id/share_btn"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:layout_gravity="center"
+        android:text=""/>
+
+    <Button
+        android:id="@+id/cancel_btn"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:layout_gravity="center"
+        android:text="@string/cancel"/>
+
+</LinearLayout>
\ No newline at end of file
diff --git a/src/com/android/settings/connecteddevice/audiosharing/AudioSharingDevicePreferenceController.java b/src/com/android/settings/connecteddevice/audiosharing/AudioSharingDevicePreferenceController.java
index dd5eb62..b0f8b8f 100644
--- a/src/com/android/settings/connecteddevice/audiosharing/AudioSharingDevicePreferenceController.java
+++ b/src/com/android/settings/connecteddevice/audiosharing/AudioSharingDevicePreferenceController.java
@@ -74,24 +74,54 @@
     private Preference mAudioSharingSettingsPreference;
     private BluetoothDeviceUpdater mBluetoothDeviceUpdater;
     private DashboardFragment mFragment;
+    private List<BluetoothDevice> mTargetSinks = new ArrayList<>();
 
     private final BluetoothLeBroadcast.Callback mBroadcastCallback =
             new BluetoothLeBroadcast.Callback() {
                 @Override
-                public void onBroadcastStarted(int reason, int broadcastId) {}
+                public void onBroadcastStarted(int reason, int broadcastId) {
+                    Log.d(
+                            TAG,
+                            "onBroadcastStarted(), reason = "
+                                    + reason
+                                    + ", broadcastId = "
+                                    + broadcastId);
+                }
 
                 @Override
-                public void onBroadcastStartFailed(int reason) {}
+                public void onBroadcastStartFailed(int reason) {
+                    Log.d(TAG, "onBroadcastStartFailed(), reason = " + reason);
+                    // TODO: handle broadcast start fail
+                }
 
                 @Override
                 public void onBroadcastMetadataChanged(
-                        int broadcastId, @NonNull BluetoothLeBroadcastMetadata metadata) {}
+                        int broadcastId, @NonNull BluetoothLeBroadcastMetadata metadata) {
+                    Log.d(
+                            TAG,
+                            "onBroadcastMetadataChanged(), broadcastId = "
+                                    + broadcastId
+                                    + ", metadata = "
+                                    + metadata);
+                    addSourceToTargetDevices(mTargetSinks);
+                    mTargetSinks = new ArrayList<>();
+                }
 
                 @Override
-                public void onBroadcastStopped(int reason, int broadcastId) {}
+                public void onBroadcastStopped(int reason, int broadcastId) {
+                    Log.d(
+                            TAG,
+                            "onBroadcastStopped(), reason = "
+                                    + reason
+                                    + ", broadcastId = "
+                                    + broadcastId);
+                }
 
                 @Override
-                public void onBroadcastStopFailed(int reason) {}
+                public void onBroadcastStopFailed(int reason) {
+                    Log.d(TAG, "onBroadcastStopFailed(), reason = " + reason);
+                    // TODO: handle broadcast stop fail
+                }
 
                 @Override
                 public void onBroadcastUpdated(int reason, int broadcastId) {}
@@ -321,7 +351,7 @@
             Log.d(
                     TAG,
                     "Ignore onProfileConnectionStateChanged, not the le profile for le audio"
-                        + " device");
+                            + " device");
             return;
         }
         boolean isFirstConnectedProfile = isFirstConnectedProfile(cachedDevice, bluetoothProfile);
@@ -330,7 +360,7 @@
             Log.d(
                     TAG,
                     "Ignore onProfileConnectionStateChanged, not the first connected profile for"
-                        + " non le audio device");
+                            + " non le audio device");
             return;
         }
         if (!isLeAudioSupported) {
@@ -347,20 +377,20 @@
             }
             // Do nothing for ineligible (non LE audio) remote device when no sharing session.
         } else {
+            Map<Integer, List<CachedBluetoothDevice>> groupedDevices =
+                    fetchConnectedDevicesByGroupId();
             // Handle connected eligible (LE audio) remote device
             if (isBroadcasting()) {
                 // Show audio sharing switch or join dialog according to device count in the sharing
                 // session.
-                Map<Integer, List<CachedBluetoothDevice>> groupedDevices =
-                        fetchConnectedDevicesByGroupId();
-                ArrayList<AudioSharingDeviceItem> deviceItems =
+                ArrayList<AudioSharingDeviceItem> deviceItemsInSharingSession =
                         buildDeviceItemsInSharingSession(groupedDevices);
-                // Show switch audio sharing dialog when the third eligible (LE audio) remote device
+                // Show audio sharing switch dialog when the third eligible (LE audio) remote device
                 // connected during a sharing session.
-                if (deviceItems.size() >= 2) {
+                if (deviceItemsInSharingSession.size() >= 2) {
                     AudioSharingDisconnectDialogFragment.show(
                             mFragment,
-                            deviceItems,
+                            deviceItemsInSharingSession,
                             cachedDevice.getName(),
                             (AudioSharingDeviceItem item) -> {
                                 // Remove all sources from the device user clicked
@@ -379,11 +409,50 @@
                                         /* isGroupOp= */ true);
                             });
                 } else {
-                    // TODO: show dialog to add device to sharing session.
+                    // Show audio sharing join dialog when the first or second eligible (LE audio)
+                    // remote device connected during a sharing session.
+                    AudioSharingJoinDialogFragment.show(
+                            mFragment,
+                            deviceItemsInSharingSession,
+                            cachedDevice.getName(),
+                            () -> {
+                                // Add current broadcast to the latest connected device
+                                mAssistant.addSource(
+                                        cachedDevice.getDevice(),
+                                        mBroadcast.getLatestBluetoothLeBroadcastMetadata(),
+                                        /* isGroupOp= */ true);
+                            });
                 }
             } else {
-                // Show audio sharing join dialog when no sharing session.
-                // TODO: show dialog to add device to sharing session.
+                ArrayList<AudioSharingDeviceItem> deviceItems = new ArrayList<>();
+                for (List<CachedBluetoothDevice> devices : groupedDevices.values()) {
+                    // Use random device in the group within the sharing session to
+                    // represent the group.
+                    CachedBluetoothDevice device = devices.get(0);
+                    if (device.getGroupId() == cachedDevice.getGroupId()) {
+                        continue;
+                    }
+                    deviceItems.add(
+                            new AudioSharingDeviceItem(device.getName(), device.getGroupId()));
+                }
+                // Show audio sharing join dialog when the second eligible (LE audio) remote device
+                // connect and no sharing session.
+                if (deviceItems.size() == 1) {
+                    AudioSharingJoinDialogFragment.show(
+                            mFragment,
+                            deviceItems,
+                            cachedDevice.getName(),
+                            () -> {
+                                mTargetSinks = new ArrayList<>();
+                                for (List<CachedBluetoothDevice> devices :
+                                        groupedDevices.values()) {
+                                    for (CachedBluetoothDevice device : devices) {
+                                        mTargetSinks.add(device.getDevice());
+                                    }
+                                }
+                                mBroadcast.startBroadcast("test", null);
+                            });
+                }
             }
         }
     }
@@ -470,4 +539,26 @@
         }
         return deviceItems;
     }
+
+    private void addSourceToTargetDevices(List<BluetoothDevice> sinks) {
+        if (sinks.isEmpty() || mBroadcast == null || mAssistant == null) {
+            Log.d(TAG, "Skip adding source to target.");
+            return;
+        }
+        BluetoothLeBroadcastMetadata broadcastMetadata =
+                mBroadcast.getLatestBluetoothLeBroadcastMetadata();
+        if (broadcastMetadata == null) {
+            Log.e(TAG, "Error: There is no broadcastMetadata.");
+            return;
+        }
+        for (BluetoothDevice sink : sinks) {
+            Log.d(
+                    TAG,
+                    "Add broadcast with broadcastId: "
+                            + broadcastMetadata.getBroadcastId()
+                            + "to the device: "
+                            + sink.getAnonymizedAddress());
+            mAssistant.addSource(sink, broadcastMetadata, /* isGroupOp= */ false);
+        }
+    }
 }
diff --git a/src/com/android/settings/connecteddevice/audiosharing/AudioSharingJoinDialogFragment.java b/src/com/android/settings/connecteddevice/audiosharing/AudioSharingJoinDialogFragment.java
new file mode 100644
index 0000000..b9646ac
--- /dev/null
+++ b/src/com/android/settings/connecteddevice/audiosharing/AudioSharingJoinDialogFragment.java
@@ -0,0 +1,127 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.settings.connecteddevice.audiosharing;
+
+import android.app.Dialog;
+import android.app.settings.SettingsEnums;
+import android.os.Bundle;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.widget.Button;
+import android.widget.TextView;
+
+import androidx.appcompat.app.AlertDialog;
+import androidx.fragment.app.Fragment;
+import androidx.fragment.app.FragmentManager;
+
+import com.android.settings.R;
+import com.android.settings.core.instrumentation.InstrumentedDialogFragment;
+import com.android.settings.flags.Flags;
+
+import java.util.ArrayList;
+import java.util.Locale;
+import java.util.stream.Collectors;
+
+public class AudioSharingJoinDialogFragment extends InstrumentedDialogFragment {
+    private static final String TAG = "AudioSharingJoinDialog";
+    private static final String BUNDLE_KEY_DEVICE_ITEMS = "bundle_key_device_items";
+    private static final String BUNDLE_KEY_NEW_DEVICE_NAME = "bundle_key_new_device_name";
+
+    // The host creates an instance of this dialog fragment must implement this interface to receive
+    // event callbacks.
+    public interface DialogEventListener {
+        /** Called when users click the share audio button in the dialog. */
+        void onShareClick();
+    }
+
+    private static DialogEventListener sListener;
+    private View mRootView;
+
+    @Override
+    public int getMetricsCategory() {
+        return SettingsEnums.DIALOG_START_AUDIO_SHARING;
+    }
+
+    /**
+     * Display the {@link AudioSharingJoinDialogFragment} dialog.
+     *
+     * @param host The Fragment this dialog will be hosted.
+     * @param deviceItems The existing connected device items eligible for audio sharing.
+     * @param newDeviceName The name of the latest connected device triggered this dialog.
+     * @param listener The callback to handle the user action on this dialog.
+     */
+    public static void show(
+            Fragment host,
+            ArrayList<AudioSharingDeviceItem> deviceItems,
+            String newDeviceName,
+            DialogEventListener listener) {
+        if (!Flags.enableLeAudioSharing()) return;
+        final FragmentManager manager = host.getChildFragmentManager();
+        sListener = listener;
+        if (manager.findFragmentByTag(TAG) == null) {
+            final Bundle bundle = new Bundle();
+            bundle.putParcelableArrayList(BUNDLE_KEY_DEVICE_ITEMS, deviceItems);
+            bundle.putString(BUNDLE_KEY_NEW_DEVICE_NAME, newDeviceName);
+            final AudioSharingJoinDialogFragment dialog = new AudioSharingJoinDialogFragment();
+            dialog.setArguments(bundle);
+            dialog.show(manager, TAG);
+        }
+    }
+
+    @Override
+    public Dialog onCreateDialog(Bundle savedInstanceState) {
+        Bundle arguments = requireArguments();
+        ArrayList<AudioSharingDeviceItem> deviceItems =
+                arguments.getParcelableArrayList(BUNDLE_KEY_DEVICE_ITEMS);
+        String newDeviceName = arguments.getString(BUNDLE_KEY_NEW_DEVICE_NAME);
+        final AlertDialog.Builder builder =
+                new AlertDialog.Builder(getActivity())
+                        .setTitle("Share audio?")
+                        .setCancelable(false);
+        mRootView =
+                LayoutInflater.from(builder.getContext())
+                        .inflate(R.layout.dialog_audio_sharing_join, null /* parent */);
+        TextView subtitle1 = mRootView.findViewById(R.id.share_audio_subtitle1);
+        TextView subtitle2 = mRootView.findViewById(R.id.share_audio_subtitle2);
+        if (deviceItems.isEmpty()) {
+            subtitle1.setText(newDeviceName);
+        } else {
+            subtitle1.setText(
+                    String.format(
+                            Locale.US,
+                            "%s and %s",
+                            deviceItems.stream()
+                                    .map(AudioSharingDeviceItem::getName)
+                                    .collect(Collectors.joining(", ")),
+                            newDeviceName));
+        }
+        subtitle2.setText(
+                "Connected eligible headphones will hear videos ad music playing on this phone");
+        Button shareBtn = mRootView.findViewById(R.id.share_btn);
+        Button cancelBtn = mRootView.findViewById(R.id.cancel_btn);
+        shareBtn.setOnClickListener(
+                v -> {
+                    sListener.onShareClick();
+                    dismiss();
+                });
+        shareBtn.setText("Share audio");
+        cancelBtn.setOnClickListener(v -> dismiss());
+        Dialog dialog = builder.setView(mRootView).create();
+        dialog.setCanceledOnTouchOutside(false);
+        return dialog;
+    }
+}