Originally Posted by
nearlysober
Assuming you are MVP Gold (MVP cannot upgrade their guest) and therefore eligible to upgrade someone flying with you, you are both eligible. Using the companion fare does not invalidate eligibility or reduce the booking class.
The question was about a mileage upgrade, not an elite status upgrade. I don't know the answer, but I assume it's the same.
But I believe that you cannot split the record into two on a companion fare. That means you must either both upgrade or neither upgrade, if I understand correctly (so there must be two U seats open at once).