I recently installed an outside wood furnace,with the rad in my oil furnace. I would like to be able to turn the fan on upstairs with a switch or another thermostat. I currently have a honeywell ct51 thermostat with 2 wires. There is an auto and manual switch on this thermostat but only works with the oil furnace. Auto

Your going to need more than two thermostat wires and maybe a new or extra thermotat to add a isolation relay for your two heating systems.