It would depend on the length of the flight and whether it was going to be just me upgraded or me and one other person.

If it were a transoceanic flight, no way am I sitting in coach - but I'm always upfront about that with friends/family when booking those kinds of trips. I'll do what I can with my status to help priority list them, let them use my upgrades (if its one person), etc. but my butt is in J or F.

If its a short domestic flight, I would try to upgrade all - and if I had to sit in coach, I figure no big deal - and if I end up separated, no big deal. I don't really "socialize" on the airplane much anyhow. I have one friend that I fly with a lot and she is mid-tier and can therefore upgrade herself but usually chooses not to - she is okay with me flying in F if she is in Y as she knows she can upgrade if she feels like it.

Sounds like last year your friend and his dad had no problem flying in F while you guys were in Y... so if the tables are reversed, they shouldn't freak out too badly.