Trying to understand

This is a (hi)story that I am not familiar with.
I am confused as to what happened to the children when they were young and why it happened.
First, I guess, the women who gave birth to these children were persecuted because they had German lovers (I don't know if any--or many--were actual husbands. The captioning had Asa say the man was her husband and in the next sentence she said they were not allowed to be married). But they say that the Nazis took these children from Norway to Germany because they saw them as Aryan. The Nazis took them after the war ended? How/why did they have the power to do this? And did Norwegians (besides the mothers presumably) try to stop this from happening? Weren't the Nazis no longer a threat when the war was over?

I'm not really sure who the bad guys were--or who ALL the bad guys were. In the film at the trial, the man mentioned that this was begun by the Nazis but perpetrated by others--(East) Germans if I remember correctly. And he made a point that West Germany was also involved--at least in the case of Katrina. If the lawsuit had been won, would Germany have been responsible for reparations to the children (and maybe their mothers)? Wouldn't German(y) try to claim that it was the Nazis who committed the act?

I hope my questions make sense. Any help would be appreciated. Thank you.