Disable one or multiple heaters by condition

[Noldyie]

I have 2 heaters. One heat pump that should stay on during night time, and another that helps to get the heat to the right level if it is to cold outside.

These 2 heaters are added as 1 better thermostat.
In specific cases (at night, when it is to cold/hot outside, ...) I want to turn of one device (trough automation) and let the other work "harder" to keep the temperature like I want to.

Now I can only turn of the whole thermostat, not just one device of the thermostat.

Thanks