Originally Posted by tods27
I'm interested in the idea that an airline won't upgrade you (AA in OPs case and DP here) when a ticket has been endorsed over to them. Don't the collect a full Y fare from UA in this case? I'd think that they would be happy to let you use your DL or AA miles. I'm curious what UA does in a similar situation. For some reason I think that I did this years ago on US with a ticket endorsed over from UA, but can't really remember.
The IATA rules stipulate the the airline that the ticket was assigned to gets the actual value that the original flight (coupon) was sold for. So if a pax was on a W fare, AA might have received ~ US$150.