Best answer by AjTrek1
Surrounds are bonded to the Playbar in pairs not as single units. In the Sonos app you can set the surrounds to Full for music. The switch from surround speaker to full on music speaker is automatic after that.
You can also control the volume of the Playbar and surrounds independently when playing music via the now playing screen of the Sonos app. You cannot use the TV remote to perform that function.