I somehow wound up with Gavelkind succession. I'd have rather have Primogeniture or Ultimogeniture, so the titles don't get split up. Unfortunately, I have a several Vassal holders that are rather unhappy with me, because I seized the Duchy titles. (They were rebellious and I left them as counts. What more could they want. Sheesh!). I'd rather have only one child inherit,(I have 5 and my oldest daughter has the 'Imbecile' trait.
). Is there any way I can change succession at this point?