This happens all the time. I regularly see, what I assume to be, family members sitting in different cabins.

I flew back from JNB with Virgin in PE sitting next to the wife of one of the Directors of Virgin (accompanying him on Business Trip)- he was in Upper Class. She said if they both can't secure Upper Class (Paying Customers always take priority apparantly) then they take it in turns. She said she's sometimes been in UC and her husband was back in Y.