It is possible to run a single thermostat with multiple wires. Thermostat (A) is connected to wire 1 (B) as normal. Thermostat (A) is also connected to power module (C). (A) and (C) need their own dedicated circuits In the electrical panel. Wire 2 (D) is then connected to Power Module (C). The thermostat is the brains of the system while the power module is a worker bee doing what it is told. The thermostat would then control all connected power modules (C) and its own single wire (B).