Thought I'd share an interesting piece of information I gleaned the other day. First Officer's wife was onboard, but in J, even though F was not full, so I had a bit of a chat with the crew about eligibility.

Captain's family - F
First OFficer's family/ Purser - J
Cabin Crew (SFS and below) - Y

I'm not sure how it works for non-crew staff. Obviously Tim Clark and the Sheikh sit in F, and I do know that Country Managers and families are entitled to J.