This is Peter.
With (A) it is a case of an unknown factor. Once bitten with (K) they are unwilling to risk having someone in the group that they don’t know. The best thing for them as a group would be to have splinter groups to look after new people.
Leave them to get on with their own remit, their group is very helpful and there is a good focus. They are not ready for a change yet, but it will have to happen.