Can grafts be added under my jaw line to improve the look of my beard transplant?

I had a beard transplant but it covers only face and chin. No hair was transplanted under the jaw line. The provider said they could not perform under jaw line. Can i actually have hair transplanted under jaw line to make my beard coverage look more natural? How many grafts are needed? Also, can i take hair from the side parts of the scalp and not from back side of scalp which was already harvested earlier?