Option 1 is indeed nesting and frowned upon. You probably will not have any issues, though, since the carriers are mixed.

FWIW, I did call the elite line tonight and had them check on a DL purchased B-class fare, operated by NW. It shows up on my itinerary as H class, but the elite line rep. checked with the WorldPerks rate desk and they said that the H class was the equivalent of a filler class or something, but NW sees it as a B class and they will award the 50% class bonus EQMs. ^