I will hold my hands up here first and state I’m not a fan of having TV audio coming from ceiling speakers and I tend to see them more for flooding a room with music audio, especially when there are 4 speakers dotted about a room connected to one Amp.

That said, a Sonos Amp can be used in two ways for TV audio:

1. To play the left/right front channel TV surround audio with a phantom front center channel
2. To ‘bond’ to a Sonos master HT device and play the left/right rear channel TV surround audio (note in this mode the input/.LFE ports on the Amp are disabled).

So you could use a Beam gen2 (master) with your (slave) Amp ‘bonded’ to it to play the TV rear channel audio to its 4 ceiling speakers, but personally speaking the rear channel audio output would not (ever) be to my taste coming from ceiling speakers, but of course that is your decision.

You could use another Sonos Amp as the HT master, perhaps with two floor standers, for the front channel TV audio and use the current Amp (slave), as described above.

My own choice would be to add a Beam/Arc or Amp (master) for the front channel TV audio - and then add two Sonos One/One-SL’s for rear channel audio, speakers set at head height (when seated) and keep the Sonos Amp for the 4 ceiling speakers and music audio only.

All speakers mentioned can be ‘grouped’ for playback of music audio in perfect sync, but please note that ‘grouped’ (not bonded) Sonos rooms will not play in ‘sync’ for TV audio. 

The various setups/rooms described above, can all be used with a Sonos Sub-Mini, or the larger Sub (gen3).

Thank you so much for a detailed response, really appreciate it.

I think to start with, I'll go for adding the beam and sub.

Leaving the amp and ceiling speakers for music.

Then later on I can add some Ones for rear channel.