Recent cold sores have left really bad scarring on chin and lower jaw What can my daughter do?

try bio oil or snapping open a vitamin e capsule and rub it on it should fade it

They will go away (slowly). GO AND GET A PRESCRIPTION FOR VALTREX NOW so that you will have it ready at the first sign of new ones about to come (normally a tingling sensation.)
you could try getting her some specialist make up to help disguise it, dermablend is very very good and reasonably priced too, have a look online. x
Try vitamin E in gel cap form.. you break them open and put it over the scar you can find them at the grocery store or health food stores they might have other scar remedies there too.
You do not get cold sores on the jaw or chin. Not sure what she had but those were not cold sores. Sounds like she might have had something like imetigo. If she has any spots left that are visible go see a doc to find out what they are as it could be something contagious that spreads. Cold sores you get on the lip only.
Massage with wheatgerm oil.
Cold sores are a form of herpes. Although on the chin and jaw, I have never heard of. Have her see a physician who can prescribe something like Zovirax creme that she can apply when she has the first feelings of a sore coming on. Depending on her age and if this is indeed a cold sore, a pill form can be prescribed to deter outbreaks.
Good luck!