Another stealth enhancement!
The end of the story...son was NOT on the UG list on my iPhone app. The SkyClub agent added him again, and he was 8 for 9 seats...now sitting behind me in FC.
I'll report on the return trip. Thanks for the point out AKC, and comments, all.
(Added) it seems like AKCs text applies to companions booked together...N/A in my case, but maybe a change nonetheless.