It seems you can group multiple switches, lights
and others but not group multiple trvs with one gui thermostat control
If you are interested, there’s a custom integration available that allows you to group climate
entities.
It might be useful for you until Home Assistant supports it natively (if ever).
I second this request.
I have multiple rooms with 2 TRVs each and the ability to group them natively, would be a godsend.
We already have native groups for other things, so why not thermostats?
Thanks for that will give it a go