All these names are rampant throughout a book I read a couple of years ago on the Borgias. Orsini, Farnese, Borgia, and one of the Popes (Alexander, I think) romp through its pages. Orsini and the Borgias were enemies, but they formed a coalition to keep the Pope in power. The Borgias (including the Pope) were Spanish and they needed the Orsinis to keep them in power in Italy. If this is the same generation, I believe that Giulia Farnese was the mistress of the Pope and the mother of the infamous Lucretia.
But, the way names were re-used, I could have the dates all wrong, and the melancholy duke could be the grandfather, or the grandson, of the people in my book.
Scorecard, can’t keep the players straight without a scorecard...