I’m not sure that your 3rd-party Receiver and the Sonos Ray will play in perfect sync for TV audio - you would have to test that in situ for yourself and see how that goes, but if you ‘group’ the Ray to a single Play-1 speaker, then ‘for sure’ there will be a minimum of ~75ms audio delay due to group buffering and so if the Play-1 is located in the TV viewing room, then you will ‘highly likely’ experience an echo-effect in that room. Of course the delay will not matter if you intend to use the Play-1 in a completely different room and away from the TV viewing room.

A way around the TV audio delay between the Ray and Play-1 is to forget ‘grouping’ altogether and instead look at the ‘bonding’ together of the Sonos speakers instead - BUT .. to do that, you will require two Play-1 speakers, rather than one, and bond them as left/right rear surrounds to the Ray. 

Before going down that route however, I would first see if the Ray plays in sync with your 3rd-party Receiver. 

I do have 2 Play 1s.  I have them as left and right currently through my connect and the S1 app.

If you’d try using the Ray for this (and I would ask why you’d choose such a convoluted set up) remember the Ray is S2 only, sou you’d need to upgrade your Play 1’s to S2. Depending on it’s year of production your connect might not be able to upgrade to S2. I think any Connect made after 2016 will be upgradable.

You cannot group S1 and S2 devices.

CONNECT’s with a date code of 1501 or later are S2 compatible.

Why are you trying to connect the SONOS kit to an AVR.?

I have my surround sound already set up through my Avr.  I only want to connect a soundbar and my pair of  Play1s for my surround speakers.  My 4 other speakers are wired to the  AVR.