Originally Posted by
corporate-wage-slave
. It all has to be on one PNR, and both passengers (if applicable) need to be in the same cabin before and after the upgrade.
By definition both passengers in a single PNR will need to be in the same booking class for a given sector, as I understand.
That's why if there's only 1 seat available in a cheaper booking class and you book for two people, both passengers are fared at the higher class.
Which means the requirements that both pax be in the same PNR necessitates the fact that they'll be in the same cabin before the upgrade, and therefore the same cabin after.