I was looking for another answer here on the forums and came across this very very very long thread.
"The plugin even offers support for multiple houses. So it is finally possible to create multiple houses and control them together."
Takes about 20 minutes to set up and works as it should. All you need is a computer (I recently went for the Rasberry Pi 400). Whilst a computer costs money, if you already have one this software is all free.
Hope this helps
This might not work. Multiple homes have individual thermostats - this plugin will just group them together under one homekit. Unfortunately it doesn't resolve the issue when you have home with one thermostat and need to control multiple individual TRVs separately - unless the thermostat itself is there as one of the devices. It will still need a lot of configuration to make sure it switches on/off when needed for devices that are not directly connected to it. I'm also not sure if you can have TRVs on the seconds account without a thermostat? Perhaps somebody could try this if they have multiple bridges to see if it can be all configured?