Sry for my english but my native language is german. My idea is that existing countries can buy regions from other countries. Example:
Austria buys the region "Graubunden" from Switzerland. The region is then under austrian control. If an other country f.e. Germany has occupied "Graubunden" so the resistance war is not started from Switzerland but from Austria and is the resistance fight successful, Austria gets Graubunden back.
To buy a new region or sell an existing region, many of congress members and many of the population of the country have to accept that proposal.
What are your opinion of my idea?