THAT was my point, that in those cases the current system doesn't fit and the only way to do something is to create new events
But I realize that talking about a system adopted to handle ahistorical outcomes of ahistorical wars might be hard to do and not seem worthwhile..
Just a thought, but couldn't something be done with the revolter tags from HoI2? There you have 'required provinces' and 'extra provinces' when releasing a country. If you add the ability to 'tag' provinces which you want to keep after conquest (like the provinces Russia kept after pushing the Fins hard enough), you can use the "required provinces" and "extra" lists to determine if a 'white peace' is possible (since in a white peace you keep the provinces you have claims on if you've conquered them, then you'd also keep those you don't have claims on but have 'tagged').
'Tagged' provinces wouldn't be same as claimed ones (in which you get 100% of the resources) of course, they would always be considered 'occupied'
You would use the 'extra provinces' list as 'provinces a country might give up, given enough incentive (ie the more you want, the lower you need to get their national unity before they even consider a white peace, if you get the country to surrender you can release it, but keep the provinces you tagged) and the 'required provinces' list as 'provinces without which a certain country cannot possible exist' (ie if you want any of those, the country will fight to the death and you'll have to occupy it entirely, you cannot release the country even after it completely surrenders unless you give up those tags).