So the "conquering duchy" would be calculated based on...the guy who starts the takeover, or the duchy to which the majority of forces in the region belong? They can be different, and that can definitely matter. On one hand there's the initiating party, and on the other hand there's the majority stakeholder. When those two are at odds, how would game mechanics solve that? Would it be arbitrarily one over the other?
It makes sense that it would be the initiating party. If you don't support his claim, leave the region and don't support him.
