Originally Posted by
Long Zhiren
I once did DEN-NRT-SIN. Due to a delay that made me miss the connection, UA put me on a DL NRT-SIN flight. I got UA credit for the DL NRT-SIN flight but I strongly believe that I would have been able to get DL credit instead of UA credit. ....
Double dipping when different alliances is very possible. Different alliance are relatively easy to manage but as sbm12 mentions, same day, using *A airlines it becomes problematic since it appears the account used for credit is the one in the record at some point after the flight, not necessarily the one at flight time.