Originally Posted by
MSPeconomist
If the GUC books into partner O class (award inventory) for the upgrade, it could be harder to rebook and maintain the upgrade than when the original fare class upgrades into Z for the upgrade.
I suspect the reality is that people will find it easier to have a DL agent rebook them into confirmed D1 space if the ticket has already been reissued for the upgrade versus the GUC (or miles supported) upgrade just having been confirmed but with no ticket reissue yet.
Once the upgrade clears AND ticket is reissued (the last part being important) rebooking should be cabin to cabin, not fare class to fare class.
This where most agents mess up. They're used to O being an award class and thus apply the logic of the ticket being an award ticket.