My theory about Oleg
So we know that Phillip's father was a guard in a prison camp, and we know that Oleg's mom was a prisoner in a camp.
What if it was the same camp?
What if, in order to survive, Oleg's mom had sex with some of the guards like Phillip's dad.
And then she got pregnant and was released and went home. Her husband raised the child as his own.
What if Phillip and Oleg are half brothers?