Already dug some about those families and big possibility Y family “female” married into Vanderbilt family. I’m suspecting she is Alva Erskine-Smith Vanderbilt Belmont = mother of Consuelo Vanderbilt who was the wife of the Duke of Marlborough as in the cousins of Winston Churchill.
Plus, check out Marble House in R.I. It was Alva’s. And the rail goes all the way there to then go into Canada. Loads of Bloodline families or elite families had “cottages” there for summer vacation. I discovered this after digging about General Flynn’s “Beaver” picture he put on his twitter header.