I'm sorry to hear about your daughter's unfortunate fall. What she has is a depressed, widened scar that is a result of a poor or non- repair of the underlying deeper tissue.
This is quite common of cuts that are left to heal without surgical repair, or if tissue glue is used alone.
She needs a scar revision which is a simple day surgery procedure about an hour long. It can be done under light sedation if she is cooperative or under GA if you wish. This is a Medisave claimable procedure.
Best Regards,
Dr Samuel Ho