Regular old DoApulia starting game, with DVIP, my sons were the the bastard, the hunchback and the other one. The law says the strongest one gets to inherit, and I decided mr. hunchback would be it.
Refused all calls for the bastard to enter the succession law, even at a considerable prestige price. When Hunchback kid came of age, I declared the KoS and granted him his own dukedom. Mr Bastard and Mr Young one were kept in my court.
Then the King dies and Mr Young inherits.

I checked again and it seems Mr. Hunchback got himself excommunicated. I'm guessing that has the same effects as being a bastard?
edit: 4k posts! Hurray me!
Refused all calls for the bastard to enter the succession law, even at a considerable prestige price. When Hunchback kid came of age, I declared the KoS and granted him his own dukedom. Mr Bastard and Mr Young one were kept in my court.
Then the King dies and Mr Young inherits.
I checked again and it seems Mr. Hunchback got himself excommunicated. I'm guessing that has the same effects as being a bastard?
edit: 4k posts! Hurray me!