2 stage, 2 zone heatpump with propane backup wiring issue

i just bought a newer home, the HVAC was installed about 8 years ago. it has a indoor heat pump with a ground sourced freon loop. We have 2 thermostats that control heat and cool with no issues. Both tstats are white rogers, with emergency heat and heat-pump options. The zone control is a honeywell EMM 3U. There is a high-eff propane furnace being used as an air handler. I can make the propane kick in only if I turn off the heatpump breaker and switch the zone control to emergency heat. From what I was reading, this zone control is not wired correctly and the gas furnace can be set to kick in as a 2nd stage for additional heat automatically, or be switched via tstat to run as gas-only. to further add to this, we installed a 22kw whole-house generator with AC shedding. The shedding just breakes the tstat Y wire. I would really appreciate any help i can get with correcting this so it can function as i think it should. I am basically looking to have the gas kick in if the house gets too cold (HP either malfunction, cant keep up with heating load, HP shed due to generator load, etc). I have photos of the current wiring.