I see a cheaper flight offered by NW (flights operated by CO) than the CO-issued ticket.

As a CO Onepass plat, what happens when I'm on a NW flight&ticket that's operated by CO? Specifically, I wonder:

- which company's revenue mgmt allocates seats into the 'F' bucket (or whatever NW calls their upgradable bucket)?
- Does EUA work? Or is it NW's EUA rules? (I believe I get plat upgrades on NW exactly the same as I would on CO? Would that include companions)