Originally Posted by
MSPeconomist
Are you sure that the 72 hour rule applies to "up faring" award tickets into FC? I would think that DL would like to take extra miles for flights where FC is lightly booked close to the travel date. There might even be grounds to waive the change fee.
Sure, they will take extra miles. They'll take all the miles from your original coach booking (forfeited within T-72) plus all the miles from your new FC ticket.
YMMV with getting waivers, as always.