Some suggestions:
1) The ability to choose the education type your child receives. At this time, the moment a child is born, they are either a spy/diplomat/marshal/etc. despite maybe having stronger strengths in other areas.
2) The ability or a tradition that allows for choosing your heir.
3) Add more family interactions for roleplay purposes perhaps, or to help explain why the 2nd prince decided to betray you and rebel with the support of your rival Kingdom cuz the 1st prince and 2nd prince never got along. Or how they're wives caused friction between brothers. Plenty of potential options.
4) Include a way to track family hierachy beyond one generation so we can at least have an idea how many grandchildren we have in line for the throne.
5) Bastards. Let's get some illegitimate kiddos up in this joint. Maybe have an option to send children to Rome or Mecca or the Crusades or to a foreign power as a hostage.