Another issue with an award ticket I booked, using my miles, but for someone else: I didn't include my Dividend Miles number in the reservation for the award ticket, since I couldn't get miles on it and I figured that it would mess something up since the name and account number for the ticket wouldn't match.

Yet a US ticket agent added my Dividend Miles number to the award ticket, without me asking for it- "it'll save money on baggage." That was nice, but does that work-- can you just put your DM number in someone else's ticket and give Preferred benefits to them? Wouldn't the US computer system catch it and cause a problem?

I called US again and had them take the number out of the reservation, so nothing happened, but am curious.