Originally Posted by bennos

Basically what rylan said, but for more detail extra seats upgrade basically with the same rules as a seat occupied by a person. Since as a Medallion you can only list one companion for an upgrade, you can't list both of your partner's seats. If she has status, she can list her extra seat, but both of her seats would need to clear at the same time. You can theoretically split the PNR, but that can cause complications since the extra seat isn't for a passenger (especially if this is the first leg of a round trip and the leg gets canceled for the extra seat due to agent error).