For the past two England games I have experienced problems with the English throne succession.

I'm always doing fine until Richard I appears. Then all the other heirs are "de-heired" and all Richard does is produce a few princesses.

In the last game I made sure every Prince was married early, but this didn't stop Richard from blazing the scene and not producing any heirs himself.

Before the above two games I never had problems. So what am I doing wrong? And can I fix the situation? Richard usually lives quite long, and in my last savegame I he is 50 and his brother is 47. But I know Richard won't produce heirs anymore (and John doesn't seem to be very active either) so what can I do?