I was successfully able to book a RT ticket on DL for 80,000 miles + $321
Never knew of this option, so thanks Dan for letting me know that
You have to be vvvveeeeerrrrryyyyyy patient, but in the end they successfully booked it.
No mileage return if you wanna cancel the flight
though date changes are free.
FWIW, Virgin Atlantic does not charge YQ on DL.