There’s nothing in the Constitution about it, but the interests of the Kennedy’s, and potentially of other political families, are covered under the “House of Lords Act of 2008.”
House of Lords Act sounds just about right.
The more I hear about all this shuffling and buddies getting good posts with good pay... well it reminds me of good ole England with sons inheriting titles and wealth. Caroline Kennedy has done nothing but be born. She has done nothing to qualify her to be a Senator, except she has the last name required to make her royalty.