LA Injection: A young patient who cannot hold still

A mother brought her 8 year old daughter to you for a dental restoration.
Local anaesthesia is needed prior to placing the filling. You've explained the procedures and both mother and daughter are fully informed and consent given by the mother.
As soon as you injected into the patient's mouth she started to move around. So you stopped and explained the importance of holding still during the injection and how it will be dangerous for both you and her if she moves.
The patient told you she understood and would like to try again. However you tried twice more and the patient could not hold still. Her mother is very upset that you cannot complete the treatment and insist you to keep trying until LA is successfully administrated.

You know the risk of needle stick injury to both you and the patient if you keep trying. What should you do?