I have two 200 amp main panels, each feeding an independent generator subpanel (subpanels have mechanical interlocks). I want to feed both subpanels with a single generator that's capable of powering the entire system. Running the hot wires seems pretty straightforward - feed one of the subpanel generator supply breakers directly from the generator, then use a split bolt or multi-wire tap to feed the other. Where I get stumped is how to wire the neutral/ground in a way that meets the NEC. I don't think that I want to branch the neutral/ground from one subpanel to the other because this would ultimately make a loop in both conductors (subpanel A -> main panel A -> CT -> main panel B -> subpanel B -> subpanel A). Yet connecting the neutral/ground at just one subpanel also feels "wrong" even though it should work just fine. My understanding is that you want all conductors carrying the same load to be in physical proximity, so I'm thinking that it make be questionable having the hot conductors separate from the neutral/ground path. If this is true then that means that I'm stuck trying to find a way to switch the neutrals, and I think that this is a pretty expensive proposition. Am I just being overly conservative worrying about feeding the neutral/ground from one subpanel to the other using the existing path through the main panels and CT? Would such an arrangment pass an inspection?