CVC 14604(a) can possibly be applied.
14604. (a) No owner of a motor vehicle may knowingly allow another person to drive the vehicle upon a highway unless the owner determines that the person possesses a valid driver's license that authorizes the person to operate the vehicle. For the purposes of this section, an owner is required only to make a reasonable effort or inquiry to determine whether the prospective driver possesses a valid driver's license before allowing him or her to operate the owner's vehicle. An owner is not required to inquire of the department whether the prospective driver possesses a valid driver's license.
Since the 15-19 year old age group is 5 times more likely to be involved in a serious injury or fatal collision than any other age band, why would you take the risk that you would not be covered and that you could be criminally charged and even sued? As the father of teens myself, I will not allow my children to drive their friends while their license is provisional or even drive WITH friends who are provisional. It is foolish, illegal, and negligent.