Its a limitation inherent in the Sonos device driver, not Rule Machine or WebCore. If you have Smartthings, you can connect your Sonos speakers and then connect them to Hubitat using [RELEASE] HubiThings Replica. The Hubithings Replica Sonos device driver allows you to control volume of a group (a feature that the regular Sonos device driver does not have), but doesn't (i believe) allow you to add / remove a speaker from a group.
Download the Hubitat app
