I recently flew two UA segments Asia to US, followed by an internal segment the following day. I had my OZ (Gold) number in the booking, and flew the first to segments that way. Since they would have tipped me over my Gold renewal, I decided to credit the internal segment to my other program (SQ), so switched the number at the gate. I logged into both my accounts today and see that the miles for all three flights have been credited to SQ. How did that happen? I can only guess there is some sort of delay between flying and the miles getting transferred, and rather than transfer to the FFP indicated for the segment, they just send to the FFP in the booking at the time of credit? I wasn't expecting this, but at least I still have my returns to credit. Any ideas what I could have done if this wasn't the case? I had always assumed it's the program on the BP that is where credit is sent.