blender retard here.
how do i add an armature from one model to another?

To be specific, when i grabbed all the koikatsu textures it turned out that my hair model has three different textures because in game i used 3 hair parts to make the model, front hair, back hair and side hair. to make it easier to uv the hair i decided to delete my models current hair which is one whole thing and then in koikatsu grab the three hair parts separately, import them into blender and add them onto my model so i can use the textures on each part.

i dont know how to add the hair though, i can delete the old hair fine but if i paste the hair object it makes another armature?