read the in depth history in the walpole forum the last few days by donna. there will most probably be real leads there.
i am a walpole with a direct linage to sir robert in norfolk, england although cannot claim on the title or fortune of the present walpoles of norfolk, england.
a direct descendant of the walpole family of fame, lord walpole, sits in the house of lords and can be contacted there via the house of lords website. no doubt the walpole of scotch plains is of a near direct line. there are feww walpoles in great britain.
if i can help further, please be in touch.
i know scotch plains well, a lovely area - my second half usedo live there. her house used to be a hundred yards from the woods and the deer used to come out into her back yard - all to become friends - at a distance!