Auto Insurance Claims: auto claim, couple cars, excess coverage

Question
My daughter had friends over and we had several cars in the driveway. They had to move a couple cars to let a friend leave, my daughter was moving a friends car and anotheer girl was moving a different friends car, the other girl backed into my daughter "neither girl was in a car owned by them" who is the responsible party?

Answer
The coverage follows the vehicle.  So the claims should be reported to the insurers for both cars.  As long as each driver had the permission of the owner of each vehicle to operate each vehicle, both insurance policies will provide coverage.  Then the insurers will investigate the facts to determine who was negligent and that policy will pay for the damages to the other car.  The negligent policy will also cover their own damages assuming their is Collision coverage.  If either policy denies coverage for non-permissive use, then you would report the claim to the insurance policy for the driver, which would step in as excess coverage.