There is no negotiating with the Polish. They are a formidable fighting force that is looking to reestablish the Polish-Lithuanian Commonwealth. There is no compromise, only who can shoot more of them. They do not fight for the Prussians, the Russians, or the Austrians. They fight for Poland. It just so looks like Prussia is going to kick the sh*t out of everyone, so they are "allying" with them right now. Should the tides turn, Posen will rise and everyone will be in revolt.