Ok my two takes.
First-Poland doesn't go through Partitions due to POD of accepting Cossacks as noble class. The result is a highly aristocratic state with 20-30 % of nobility and large serf class. In XIX century the serfs and some priests come with liberation teology combining elements of communism and peasant free-comune ideas. When Communism erupts in XX century the Polish society revolts and becomes one of the first communist nations, with close ties to Soviets in Russia.
Second-CP victory scenario and implementation of Mitteleuropa plan, as well as discrimination of Slavs and treating them as second class citizens serving German landlords and industry. This situation eradicates differences between Poles and Ukrainians, while Soviet Russian communism adopts the idea of liberation from German dominance with communist ideology. The Second World War is led under the banner among others of panslavic communism.