Play 3 For 5.1 surround

I'm not sure I understand. You intend to replace the PLAY:1s with the PLAY:3s? Why? For most of us, PLAY:1s are more than sufficient for surround speakers, the PLAY:3 would be considered an overkill at worst, more expensive than necessary at best.

Oh... a thought just occurred to me. Are you under the impression that you can set up the PLAY:3s or PLAY:1s as front left and right speakers? Sonos doesn't support that configuration. The center, left and right speakers are all inside the PLAYBASE, and the signals can't be split out.

If you really want to add to your current experience, keep the PLAYBASE and two PLAY:1s, and add a SUB, which will rock you house. That's the true 5.1 experience in Sonos parlance.

I’m wanting to add two play 3’s to my current system of a play base and 2 play 1’s is this something that is doable or not.

Yes, you could add them as another "room", but not in the same room in the Sonos software. A PLAYBASE already consists of a Right, Center, and Left speaker, so the only things you can put in the same "room" is a pair of surround speakers, and a SUB.

Thank you for finally clarifying the 5.1 set up. Historically, a 5.1 set up included a distinct left and distinct right front speaker, a center speaker and 2 rear surrounds (plus the sub). Apparently, the Sonos system COMBINES the front left,right and center speakers into ONE beam/bar/base. I FINALLY get it! Thanks!

That's actually a fairly standard setup for a "soundbar". When they have 5 physically distinct speakers (or 6, including the sub), they tend not to call it a "soundbar". The ubiquitous "they", of course.