Maybe the lawyers here are being smart about this.
1. Family of deceased employee wants to sue the employer for $15M.
2. Michigan law does not allow them to do this, so they sue the owner of the vehicle.
3. Michigan law DOES allow a customer to sue a business establishment, so the insurance carrier for the vehicle owner files a third-party claim for contribution from the business owner.
4. The family of the deceased gets $15M from the vehicle owner. The vehicle owner gets $15M from the business owner to cover his loss. Justice is done.
THE END.
One would hope your scenario is how it would play out.