I need to book a back up flight from Denver to LAX on Delta. My current flight on American leaves at 4 PM. There is a Delta flight that leaves at 6 PM or 630, I forget, but because of extenuating circumstances I need to be able to get back to LA that night. If the Delta flight is only two hours after the American flight, can I still cancel the Delta flight if the American flight leaves relatively on time? I think I would book cash refundable because then I would not have to speculatively transfer American Express points to Delta to cover the backup flight