Hi Robona, is that a Play:5 gen2 or gen1? If it’s the gen2, do you just have the one of them or is it a pair of them?
The reason I ask is if you have a pair of Play:5 gen2 speakers, you can have them bonded as the surround speakers for your Playbar, then they wouldn’t be two separate “rooms”
As to preventing the group from separating when you play TV audio, under Settings > System > (Playbar room name) you can toggle the TV Autoplay so that it doesn’t ungroup on Autoplay. This would stop it from dropping groups when the TV is on.
The remote will only adjust the volume of the Playbar’s room, so if you have a pair that you set up as surrounds, the remote will adjust the volume there too, but if not, than the remote can’t change your Play:5’s volume.