Yes I have heard of this. I personally believe Margaret Gragg is the wife of Benjamin I. She was too old to be the wife of Benjamin II who was born 1755. Margaret was born 1725 to 1740.

The story all the Kimsey's try to tell fit the Graggs. They were exciled from Scotland after the Culleden war and dropped the Mc or Mac from their name after arriving in America. They were the McGreggor Clan.