Here’s a fun data point.

Wife and i flying paid J. Third companion on different PNR (obviously) in Y on a miles ticket we got her. All 3 check in with AF at JFK. I ask, nicely and not expecting anything, if there’s any way we can get her into J with us. AF agent does a bunch of typing and a minute later hands us a new BP.

Voila! Our companion was with us in J. Go figure.

That one made our day. I wanted to post details here at the time, but decided against it in the event it might cause some blowback.

ETA: She was no status and didn’t even have an SM#. In fact, this was her first-ever international flight.