Can I ad 2 play 5's to my Sonos play bar and my play 3's

Yes you can add up to I do believe 50 speakers onto on system. You can only have 2 speakers added to the play bar for surround sound which makes it a 5.1 system unfortunately Sonos doesn't offer the 7.1 surround sound set up yet hopefully they will add that feature in the future. You can have the gen 2 Play 5s as surround but you can not have the gen 1 as surrounds. You can still group all your speakers together to play the same tv sound or music. You can stereo pair the gen 1 Plan 5 to gen 1 Play 5, and stereo pair the gen 2 Play 5 together but you can not stereo pair a gen 1 and gen 2 play 5. I hope this information helps you out.