@Emil I believe the groups that you speak of are the lower g groups. Yes, they are dynamic and can change fairly easily (too easily imo) and I think that's why Sonos now has Groups (upper G). In the Sonos app you can create a Group, give it a name, and select the speakers/rooms that you want assigned to that Group. Then when you go to play music, instead of selecting specific speaker/rooms you can select the Group. For example, I have groups named Inside and Outside. The speaker/rooms in those Groups remain the same regardless of how I might dynamically change them throughout the day. But sometimes I might only want music in the Office or Den, which I might dynamically connect as a group. So it seems the question is whether or not Sonos exposes these Groups in their API? And can you send a play command to a Group? Or simply a "player"? I don't know.