Great mod once again, playing it non-stop.
Just a thought:
Playing campaign game with Portugal I joined the Allies in WW1 and did some opportunistic land grabs of a few South-West African provinces and island hopping in the Pacific ti take pointlessly small German-controlled islands. Once I take these provinces over, the flag becomes Portuguese, but when the historical Versailles Treaty event occurs with harsh terms for the Germans, all territory is distributed as in history (ie. My African gains to S. Africa, Pacific islands split between UK and Japan).
Would it be possible to own some of the provinces you take over throughout the war in a victorious peace treaty? This would only really occur as a minor joining an alliance but I still think it reasonable to earn 3 or 4 provinces, no matter how unimportant, if I joined and fought in a victorious war alliance.