Or at least to add CBS to an existing war and have peace negotiations like eu3.
Anyway, I'm guessing this is a glitch but my new king in my Wales from Dublin game can marry his own sister, or is it just like a matter of I'm the king I can do what I want? I mean the empress of Byzantium is eligible even if not great stats but she is still a child after all but she won't consent to marriage unless matrilineal, although I guess that makes sense.