They both run S2, so they can be grouped. You’d need a second PLAY:3 if you planned on using the pair as surround speakers, though. Given that the PLAY:3 hasn’t been manufactured for many years might make that challenging.

Note that if grouped, the PLAY:3 will play the TV input to the Sonos Ray slightly delayed, but when streaming music, they’ll be in sync. 

Depends on what you mean as “use”.  If you mean to group with a Ray to play in sync for music and slightly delayed for TV?  Yes.  If you mean for surround, you would need a pair of Play:3’s.  You cannot add a single surround speaker to a Sonos soundbar. 

Thank you. Now I know I need to buy two.

I’d be going for the Sonos One SL to use as surrounds, they’re much more available since they are still being manufactured. And I can’t really tell any difference between mine (I own both). Probably cheaper, although I’m not sure where I would source a pair of PLAY:3s these days. 

Already found $100 each. Just wanted to make sure they would work