Originally Posted by
Mwenenzi
Yep.
Fly UA, and collect the UA ff miles.
Then put in a claim with DL for "original routing credit" for DL ff miles due the delayed/rerouted flight.
I would not count on getting UA miles. Numerous reports of IRROP related re-bookings now getting flagged as non-mileage earning now that mileage earning is based on fare paid. OP would be eligible for ORC from DL.