If you create a stereo pair, they will be known by their roomname, so if you call the room “stereo” you can say “play x in stereo” and x will play to that room. You can then group multiple rooms and have the music sync’d in both rooms. 
It may be clearer to call the paired One SL’s by a “geographical” name such as Lounge. 

I’d probably say ‘on’ rather than ‘in’, but you could just test and see which works better for you and your system. 

Ok. I have a playbar, sub and two play 3's in a home theater ròom, and a one gen 2 in dining room (only speaker with mic) and soon a pair of SL's in let's say a lounge.. Ni matter which configuration I am allways able to control any of my rooms with a single voice assistant enabled speaker?

Thank you both very much

Neven

Assuming the mic can hear you: yes. If you don’t specify a room the command will apply to the Dining Room speaker; if you specify “<command> in/on Home Theatre” it’ll play to the Playbar+Sub+Surrounds whilst “<command> in/on Lounge” will affect your pair of OneSL’s. 

Thank you very much. It is an open space so it want be a problem.

Neven