My grandfather and grandmother were Nicholas Tangney and Bridgette Norton, who lived in Wollaston, MA. They had seven children: Patrick (my father), Nicholas (your grandfather), Francis, Joseph, John, Lulu, and Catherine. The rift was over business, and concerned Nicholas, John and Patrick. We had no contact with Nicholas' Milton branch of the family for many years. The only remaining member of that generation is Catherine Tangney Edmonston, 90 years old and living in Stonington, CT.
My brother, William Tangney (also Patrick's child) went to Ireland many years ago for the purpose of researching his ancestry. I'm sure he has some information about Nicholas' ancestors, but he does not use the internet. He is a disabled ex-journalist, living in Naples, FL.
Before the family rift, I was friendly with Imelda (Milton branch), as she was a cousin about my age, and I stayed with the family at their Harwichport place one summer.