Not sure if I understand what you are trying to do fully. Are the objs high poly or low poly? I think if you want to get uvs and textures off a high poly object from the sculpt room you would have to retopo the obj and bake them out. If you already have the obj you could import them as a retopo mesh so you don't have to redo it by hand. Then if you have separate pieces you can just stitch the retopo meshes together.