@queenmeow I am not advanced in blender, only in unity. I only know how to sculpt but I don't know anything more than that and I don't have the time to learn anything extra from blender. I just sculpt the matching body to get the best possible match to the creators edit of the same body and do a body swap in unity. You can always re sculpt the body that I used by just putting the FBX in blender and try to make blend shapes to make it work with clothing.
