This is just a quick tip that might help those who are wondering about how duplicating parent-child hierarchies works in Blender!
So the question is how can you duplicate a parent and it’s children in Blender, so that the duplicated children form a child relationship to the duplicated parent instead of the original parent?
And the answer is:
Blender is smart enough to do exactly that when you simply select the parent and the children and hit shift+D. The duplicated children will now follow the duplicated parent!
If you want to make duplicate children that follow the original parent, you simply duplicate only the children and Blender will keep the child relationship to the parent intact for the duplicates! So Blender is actually working very logically with duplicated child-parent hierarchies!