If i was you i really would force that. In the netherlands was it kinda like this (for a state, but you can use it for a city or castle) A represention of the people, church and (don't know how to say it but we now it as adel (people with important blood

)) They chose a guy who was the boss of the army and a guy who was more boss about the city itself and had more influance at things like laws and stuff. The whole netherlands where ruled by a represantion of all that places. So all the bosses of army, and the other guy, and 3 guys from the goverment. They decide about really important laws and foreign policy. If you do something like this you have to have 1 army ruler, 1 city ruler and 10 other goverment guys. In a castle something about 1 guy for the castle and army. And 5 people in the goverment.