Congress Poland. Real Union Mod
Congress Poland is a Real Union state now.
Real Union is a new subject type — a mix of personal union and a puppet/dominion.
More tightly controlled than a personal union. Subject transfers 15% of their income to the overlord.
Real Union does not allow more than three laws different from your overlord under normal circumstances. There are special events for this.
It is Now even enjoyable to play Poland!
More details on Paradox forum:
https://forum.paradoxplaza.com/forum/threads/congress-poland-real-union-mod.1570939/