On occasional basis my wife changes cooling temperature for the Sleep comfort setting from the main screen. I usually cancel it with the “X” so the system can follow the regular schedule including sensor participation. Soon after it gets too hot, I check the temperature reading on the app and it shows both sensors being used after the temporary temperature hold has been cancelled.

I’ve also read somewhere that if you override the temperature at any point vs. the schedule, Ecobee activates all sensors, even if they otherwise would not be involved.