This might be a feature request that would improve usability of the Sonos system. When you have grouped some Sonos speakers and the TV is in this group I would like to adjust the volume of the group using the TV remote including muting. Scenario is when a phone call comes in or similar case when you need to mute or adjust volume level instantly.

Technically this should be feasible because right now the TV remote controls all 5.1 speakers through HDMI ARC. And the Sonos system knows which speakers are grouped together. Volume adjustment when using the remote should be the same when adjusting the group volume bar in the App. 
Of course this feature should be optional managed in settings.