>>43479879you don't necessarily need to combine the mesh. You could just align them, make the transplant object parented by the target so that it moves together in object mode, then add a modifier that binds it to your target's armature. This will make it move it with the target object (e.g. when you try to move the neck). Here's something I happen to already have and the whole setup.
However, this kinda makes posing within the transplanted object itself not possible if your target object does have the exact same bones. Thorton's end of the hair is modified by the bones THair and LHair. Noland doesn't have those so when the hair gets attached to him, they're just gonna stay like that. This is mostly a problem if your target has less armatures than your transplant. A solution to this would be copying LHair and THair to Noland, but when I try ctrl+c/ctrl+v it doesn't seem to work, so my amateur ass just decides to just make new bones (another brute force way is directly editing the mesh). This is probably inefficient if you have a lot of missing bones though (e.g. transplanting long hair to a short haired person)
