You can usually move items around within the category folder. So you can rearrange props as long as they stay in props .Remember to move the thumbnail and pp2 file together . Same for poses/figures etc.

Do NOT move anything in the runtime/geometries or runtime/textures folders

There are SOME props that have the geometry in the same folder as the pp2 file. Dont move those either , or you have to edit the file location in the prop file .