A suggestion on cores. Lets have countries have a Core Rating for each province. The higher their rating the more secure the claim to that province is. Only the country with the highest Core Rating would be able to seize the province in a war without getting BB-points. Other countries with a Core Rating would get a BB discount depending on their rating.
Once you own a province your Core Rating will slowly increase say by 1 every 10 years. Likewise your Core Rating would increase in the provinces owned by a vassal say by 1 every 25 years. Provinces under rebel control would decrease the Core Rating of the owner, when the Core Rating is under another claim holder the province might desert. If Core Rating drops below a fix amount say 10 the province might proclaim independence if they have a revolter. The new country would have a Core Rating of 10 for every province under its control when it proclaims independence.
It should be possible to build up claims in provinces controlled by enemy countries through diplomatic means.
Once you own a province your Core Rating will slowly increase say by 1 every 10 years. Likewise your Core Rating would increase in the provinces owned by a vassal say by 1 every 25 years. Provinces under rebel control would decrease the Core Rating of the owner, when the Core Rating is under another claim holder the province might desert. If Core Rating drops below a fix amount say 10 the province might proclaim independence if they have a revolter. The new country would have a Core Rating of 10 for every province under its control when it proclaims independence.
It should be possible to build up claims in provinces controlled by enemy countries through diplomatic means.