Currently, we don't support playing synchronously with our Linkplay multiroom; you can use the Google Home app to group other Chromecast-enable speakers to use it:
a. Make sure your mobile device or tablet is connected to the same Wi-Fi or linked to the same account as your Chromecast, or speaker or display.
b. Open the Google Home app.
c. At the top left, tap Add and then Create speaker group.
d. Tap each device you want to add to the group. A check Check will appear next to each device you select.
e. Tap Next, enter a name for your group, and save.