I have a house that is I use a coal stove to heat in the winter, but the heat from the stove does not make it into the back bedroom. I want to hook up another thermostat back by the bedrooms to work the gas forced air furnace. However, I want the main termostat to stay where it is for the a/c which also runs off the forced air furnace. Any suggestions would help

No biggie.

Use the terminals G, Rc/Rh(jumper) or R, Y on the main tstat. The main tstat would control fan only operation.

Use Rc/Rh(jumpered) or R and W on the aux tstat.

(C) Common is optional in both cases, saves your batteries.

The fan is controlled from the cooling stat because in that case the thermostat controls the fan. In the heat mode the furnace controls the fan, so G isn't needed.