Control room temperature with 2 Danfoss & 1 temp sensor

[hubschrauber]

After reading so many manuals, I feel stupid as I am still incapable of controlling heating in my room.
Set-up:
RaZberry with Zwave 2.2.4
3 radiators, each with its own Danfoss thermostat
1 temperature sensor on the wall

All I want is to be able to set a temperature for the room. Then the 3 radiators should be turned up or down to reach the desired temperature and then keep it.

Setting all thermostats simply to the desired temperature does not work, as the room is weirdly shaped and badly insulated. Depending on outside temperature and wind, I may need to put them to 25 degrees to have 20 degrees in the middle of the room. On nicer days its sufficient to set them to 21 degrees.

What app to use? How to set the parameters?
I tried ClimateControl and AdvancedVirtualThermostat but could not figure out how to do it.

Thanks a lot,
H