If you can't get things working as you want with the hardware you have, you could consider a different approach. I have seen thermostats that have a remote option built in. If you get such a thermostat, the second unit can be set up as a remote control that will connect directly to the first as is. I didn't review the thread (read it a while back) so I might be forgetting something, but as I recall you have multiple heater strips that you want to link together with an appliance module. Seems to me that if that doesn't work, using multiple thermostats that can talk to each other might work out for you. I'll try to find a link to an example model.