I don't know that you can back up your first sentence. I'm pretty sure the museum in Warsaw claims that they did plan to work together. Also, the museum shows part of a TV show from after the war which served as Soviet propaganda. The TV show rewrote history to say the Soviets fought alongside them. My Polish friend is in his mid-30s like me and explained how they were still showing this old TV program when he was a child in the 80s. Now he knows it was a lie.