Hello, I don't know if it's a problem with the mod or with the game, but it never happened to me in base game and haven't found any problem like this on forums. So my king died as Flanders and had quite some children, his heir takes the throne (everything is still ok), but then I married of the wife, of my deceased king and mother of the actual king, to an English noble and can't see my family tree anymore. I only see a little tree that exist of the father of the deceased king, his daughter, his daughter-in-law (lady I married to English noble) and their husbands. I'll see if I can link an image.