Well, yes, that would be the outcome.

But then, that would not make me terribly happy.

Actually, this is the standard situation when I get a revenue ticket, upgrade on the AC transatlantic legs, and end up in Y on a few short legs in Europe. While she uses an award and flies in front all the way.

Occasionally she manages to talk the FA to let me join her though. Usually after the meal. But it's getting harder. We'll see how Aegean is in that respect in a couple of weeks.