Thanks! I should wait till I complete the trip, and then add the US Air miles first, followed by the UA miles ? I ask because the UA confirmation number has both outbound and inbound flights linked to it, while the converted US confirmation number only has the inbound flight linked to it. I'm worried that if I add my United MP number while checking in, that info will go into records for the round trip and I won't be able to claim BAEC points for the return US Air flight.
Thoughts?