Originally Posted by
xliioper
Ah, I understand what the issue is now. In order to be comp upgrade eligible, both you and companion must have a DL Skymiles number on reservation. A companion with an FB account associated with their ticket will block both of you from upgrades. Comfort+ is a separate fare class on DL and not just an add-on seat selection like other airlines (comp upgrades to C+ come from SU bucket/class on DL). If you don't meet the upgrade rule requirements, the auto-upgrader won't process upgrade (and an agent will not be able to override it).
Hmmm, so if I created a SkyMiles account for my companion, tagged it to his flight and grabbed the Comfort+ seats, would I then be able to switch his FB number back in without losing the seats? More a thought than an actual question, unless anyone actually knows the answer.