I am playing as the Doux of Athens. I have two sons. One of them I married of in a normal marriage to the Duchess of Cyprus and the other I matrilinearly married off to one of the daughters of the Doux of Epirus hoping to knock him out of the succession since I have Gavelkind. I recently conquered Chandax in a holy war with one of the Muslim leaders and was able to create the title Doux of Crete. It seems the son that I married off matrilinearly is now the heir to that new title. I'm not sure how that's possible. I've confirmed again under his character screen that he is indeed married matrilinearly. How can he be a claimant to any of my titles? Is that a bug? I would just kill him off but then I'll lose the alliance with Epirus which was the whole point of the marriage to begin with!