Sarah Ferguson allegedly had a “friends with benefits” arrangement with Sean “Diddy” Combs, and once took daughter Princess Eugenie to one of the rapper’s infamous parties.

That’s one of many wild claims made by sources in “Entitled” by author Andrew Lownie — one of which alleged in an excerpt published by the Daily Mail on Friday that the former Duchess of York “made no secret how she wanted to marry someone in the US who was wealthy and powerful.”

Speaking of Jeffrey Epstein — with whom Ferguson and ex-husband Andrew Mountbatten-Windsor allegedly had friendships — a Palm Beach, Florida, source said, “If Jeffrey popped the question, she would have said yes. Even after… he was convicted of being a sex offender.…