Appointing lords is one of the duke's primary powers.
Food is a lord's primary resource.
You see the imbalance if we arbitrarily add power to solve a single side of the problem?
If a region remains without a Lord for more than a week, allow for a ruler to appoint a candidate. This would cost the Duke prestige as it appears he does not even have power over his duchy. Also give the Duke the power to dispute any such appointment, along with prestige loss for the Ruler. The Duke will lose prestige over time if the disputed lord remains in power, and the ruler will lose a significant amount of prestige if the appoint lord loses the region for some reason. The Duke can withdraw the dispute if compromise is reached, or the dispute ends if the Duke or the Lord lose their positions.
