So something like this wouldn't work than?
In your setup, if I do the 2 way valves with the normally open and normally closed, I'm not sure how that would work. If one valve closes, how does fluid flow through the other line? Are they two completely separate systems, but controlled by the same thermostat? Is there a tee somewhere where if the valve closes, the pressure will force the ATF into the other side of the tee and go through the other side of the system?