I'm sure lots of folks do and generally others are never the wiser. I did, however, see an unusual variation on a recent LGW-RDU flight. Dad was in F, two daughters were in J, and mom and another daughter were in Y.

I probably would have never noticed had mom not attempted to self-upgrade into an empty J seat. The GA caught her while doing the head count and told her it was up to the FAs but that she (mom) probably wouldn't be allowed to stay. Sure enough, the FAs sent her back to Y.

What the heck out of me was that had the mom succeeded, one daughter would have been left in Y by herself.