I would be very firmly of the view that a membership would not be required.
That's for all your info on this Graham and its a topic that I've been watching closely.
I agree with your thinking here. If a 'friend or family' member doesn't need to be a member though, what process will you need to go through to register that person as the person that's taking the seat?
The reason I say this is that a month or so ago, as a member, I was unable to go to a game because I was sick, so my cousin (who doesn't usually go the game and I wouldn't think to have him as a 'registered' person) went instead.
Would I be able to do this in the future or would it likely only be people on the registered 'friends and family' list that could go in this scenario? The question then is that if this is the case and none of them could go due to other commitments or them already going the game, I end up £45-55 down and a seat goes empty.
It's rarely happened for me, but I assume that spread over 130,000 members and people having work, kids, illnesses etc I'm sure there'll be many situations where people are unable to attend last minute.