The Child Protective Services unit in the county of residency should be involved with this. Both children would be considered endangered by their actions and "freedom". Father should ask his county for assistance. The child has committed a crime whether father wants to be involved or not. Simply driving the car with no license is good enough for that. Once child protective services or any county authority gets involved, the matter will to some extent leave your hands. This needs to be carefully considered. For example, why did the boy do this? What do YOU want to happen to boy for doing this? If you have no control, the best thing for the children is to report this asap to prevent them from getting into deeper trouble.