Eileen, I wouldn't bother asking for proof that James and John are the brothers related to Isaac etc etc. No one has it. As far as I can see one of the best attempts to discover the answer was done by Stephen E Henthorne. Well done to him for trying but he is no doubt limited to what he can do by distance and time.
I am sure the answer is on this side of the Atlantic so it comes down to reseachers in Englad to sort out the problem. As you know there is really only you and I that do anything and Peter Rathbone in the past.