What are those "families"? They have names so name them.
No need to that. Simple `forensics` of history suggest that there is continuity of interests, ways to preserve and increase power and wealth. So if something was possible, it did happen. Meaning, magnates of the Roman Empire did manage to preserve families in a new environments. Old families survived, live and rule.
So names, original, with lineage to the oldest Roman and Western Roman magnates, if you insist, are, among others: Orsini, Colonna, Habsburg, Hohenstaufen, Welf, Thuringia, Plantaganet, Holland, Ivrea, Nassau, etc.
And, dobri brate, you are naive if you think that some of them, most of them or all of them, don`t rule Vatican.
Now, well, its also possible to overthrown them or replace them or eliminate them. But I doubt. We Serbs have a proverb `Vrana vrani oci ne vadi.` /Raven do not take out eyes of other raven/. So, ways of rule of ultimate rich and powerful aren`t to exterminate each others but to intermarries.
For that, I can talk to my cat.
Don`t talk to cat. You can faster go crazy there then here.