I inherited models and drawings that are not clearly organized. We are a 2 person department and before me it was only 1 person. I am working hard to structure our Assemblies that makes sense to our production department and upper management. Because of this I need to restructure the assembly files.

We have a product that is our top level assembly and then random parts and assemblies where input as changes where made. I want to completely restructure so that top level product is almost entirely sub-assemblies. I need to be able to move a part from a sub assembly to another sub assembly. I tried click > drag but it wont allow me to move it anywhere else, I cant even change the order in  the sub assembly.