Thats not a bad idea Hannelore, restricting the number of members a fellowship can have rather than the number of fellowships one person can be in.
Of course theres problems with that too, Big Bosses might say its unfair, they need so many members for this that and the other... and there would also have to be a limit on the number of fellowships one person can run.

But it seems to me that whatever rules Fencer decides are best, there will be people who aren't happy with them.