Would this scenario be plausible? :
In the 1790s, Prussia decides to allow Russia to annex more of Poland (specifically up to Prussia's 1815 eastern borders in our TL) in exchange for Russia allowing Prussia to annex both Lithuania and Courland. Then, after the Napoleonic Wars have ended in 1815 (or whenever), Russia annexes Posen Province (which was previously Prussian) but allows Prussia to keep both Lithuania and Courland.
Anyway, is this plausible?
Also, if so, how would Posen develop under Russian rule and how would both Lithuania and Courland develop under Prussian rule?