There was an interesting idea in a timeline that sadly did not continue. In it, Enoch "Nucky" Johnson married Rose Fitzgerald, rather than Joseph Kennedy marrying her. Enoch Johnson was the inspiration for the television series Boardwalk Empire. He was a boss in Atlantic city who was heavily involved in Republican politics, as well as the various illicit activities and underground connections of the city. Rose Fitzgerald was the daughter of the Fitzgerald family, which was very powerful in Boston and Massachusetts politics and with the Irish community in that city.
The union of the two is essentially a novel way to get a political clan (despite it not being a Kennedy family) which is actually involved in organized crime and corruption. As well as having a John Kennedy analogue who is a Republican rather than a Democrat.
So what if this came to fruition?