Scarring after scalp surgery

My husband had scalp surgery about a year ago to remove nevus sebaceous. The dermatologist said he could remove it and a straight line scar would result with hair on both sides. The first surgery resulted in ulcers that had to be cut out, but when the ulcers were cut out the skin couldn't be pulled tight enough to entirely stitch together so there was an open spot in the center of the wound that scarred and had to be removed. Since then my husband has had like 6 other surgeries because the skin will seam together but will then stretch out creating alot of scar tissue and the dermatologist keeps cutting out the scar tissue. He's tried alternate stitching and incision techniques and even dermal punches on part of it. We just keep getting scar tissue.

At this point we can't go anywhere else to get this fixed because it would just be a cosmetic surgery so insurance wouldn't cover it. Insurance covered the first one because nevus sebaceous is potentially cancerous (his was benign). And the dermatologist hasn't been charging us for the fixes because he's very frustrated that it hasn't turned out right.

Is there anything we can do to change the bodies chemistry (supplement or topical cream on the wound) to keep the skin from stretching and making a big scar?  

Any help would be appreciated. The surgeries are quite painful for a few days and my husband is ready to have this bald scar gone!