Audio sink group

OH 3.1.0M4
CentOS 8

I just added two Sonos One SL speakers to my setup and they’re working so far. I’d like to be able to treat them as two separate sinks along with them as a pair.

I want some rules to trigger an audio file getting played on one or the other or both. But so far I haven’t been able to figure out how to create a group that will appear as a sink when I define the action for a rule.

Is that possible or do I have to write a second action in a rule if I want it to sound off on both speakers?

IMHO you would need to group them just before sending the play command. Each player is detected by openHAB as a single sink, a play command is received by such a player. If this player happens to be grouped to others the sound will be played on them all. In other words you are always sending a play command to a (single) player.
If you want to send a play command to several players, use a rule that first groups them and then sends the play command.