Is it possible to alter the files so that the underage male characters will be selected heirs? There are a lot of oddities coming from uncles being chosen as heirs, like that portugese family tree further up.

I had the same thing with the spanish once. What happened, was this:

1. My king died without an adult heir
2. Power passed to his brother
3. He also died with an heir
4. Thus, power passed to the non-family general you start the game with, Vasco. When that happened, my family tree looked like the portugese one.

Is it possible to mod, or are there, I'm thinking it is, hardcoded limits?