My current ruler holds three kingdoms: France, Navarra and Burgundy. That some vassal want the crown authority lowered and create a faction for it: fine. But why on earth would the Duke of Champagne, part of the kingdom of France, create a faction to lower the crown authority in... Navarra!? That some vassals outside the concerned kingdom would join such a faction, to weaken the king so to speak, could be understood, but that they would spend time, plot, recrute etc to get a result that will ultimately not get them anything makes little sense to me.