I'm trying to combine two old round style Honeywell thermostats into a new single Honeywell 7600D thermostat. One of the old thermostats controls the central forced air cooling, while the other old thermostat controls baseboard hydronic/boiler heat. All components are 24V. Each sheath has 3 wires only (R,G,W).

The heating system has 6 zones controlled by Honeywell V8043F1051 valves. I'm interested in only merging one of those zones with A/C into a single thermostat. The cooling is conventional compressor/air handler (no heat pump).

Current wiring is as follows:

Heat Thermostat to valves
R/RC --> red wire --> THTR
Y --> white wire --> not connected
W --> green wire --> TR

Cooling Thermostat to Compressor/Air handler
R/RC --> red wire--> switch/power
Y --> white wire --> cooling
G --> green wire --> fan

On the Honeywell 7600 thermostat can I connect as follows?
From heat:
red wire --> R
white wire --> leave unconnected
green wire --> W
From cooling:
red wire--> R
white wire --> Y
green wire --> G

In this case I'd be combining R to the same post which I'm assuming is not correct. Can I use the R from the cooling system to send current for heating (w) switch? Is there a way to wire these up to this or any other thermostat? Any guidance would be greatly appreciated.

Thanks!