How can I reorient an STL object to align it to a second STL object, where both STL objects do not contain the same information?

I have two STL files here that contain the information of different parts of a human ear. I would like to automatically reorient one of the objects so that it is merged with the other object as good as possible. The manual attempt can be seen in the picture below. The STL Object "fv" consists of "faces" and "vertices".

I assume that it might have something to do with maximising the intersection of the area of both objects.

It would be great if someone could help me out.

Thanks