Joan was treated much worse than any of the Kennedy daughters and daughters-in-law. Ethel was independently wealthy. Jackie had the strength of character to make the rules on her own terms. Joan had neither of these attributes and, worse, all the women in that family were jealous of her stunning beauty. From beginning to end they treated Joan like crap out of jealousy and pettiness.
Ethel was repeatedly sued for non-payment of Bills.
Kennedy Women by Laurence Leamer