FUE procedure, if done by the new techniques and small punches sholuld not leave any scar. The scar of large punches from past or in case of the patients prone to make hypertrophic scars (rarely reported after FUE), hair could be transplanted into the scars. An alternative option is to implant pigments that we do it with our SMP procedures for any type of scars.
Harvesting follicular units via the FUE (follicular unit excision) technique can be used to remove hair from the chest and transplant to any other area of the body. In your case, you had surgery and now have scars in the donor area. It is definitely possible to harvest body hairs to help camouflage the scars in the back of your head. It is vital to try to match the hair direction when transplanting to the donor area you don't want hairs growing in all directions when they should be directed downwards. It is important to go to a physician with extensive experience with FUE in order to do this type of advanced work.