I wouldn't laugh at you. I once managed to design a TTL logic circuit (can't even remember what it was for now) and then realized I could simplify the dozen or more gates I used down to about three with the redundancy I'd designed into it. Oops!
The idea of a single relay fed from each circuit via a diode occurred to me as well, but I'm not sure whether the NEC would have anything to say about linking two circuits together in this way. And with the aux. fan & relay wired from the two vent fan outlets, you'd end up using a neutral from a different circuit for one of the relay feeds, which I'm sure would be an NEC no-no (it would here be here anyway).
One other question, Virgil: Why "ice cube" relays? Because this sort of relay is probably about the same shape and size???
