Just to update this: it turns out that the intent of these kinds of predicates is to filter the primary entity. The mental concept is: decide which entities you would like to return, and return them. EF is apparently not designed for this kind of deep predicate application on child entities.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.