Since you've already flown it you're probably hosed, but why would having ~49k rollover be preferable to having DM for the next 15 months?
Originally Posted by
SeattleSon76
Sign up for an Alaskan account, or some other partner airline, and just have them sub in the other account#.
Alaska flies planes, Alaskan makes beer.
That said, this would have been the easiest way, though you may have run afoul of DL for using your DL # to book (and presumably get free EC etc) then switching.