Can a person add their auto insurance to your policy with out your consent?

Of course not. Also note that you cannot insure a vehicle that you do not own. If you do the company will probably not pay a claim because you do not own the vehicle. They also cannot pay the owner of the vehicle for damage because that person does not have contract with the insurance company so overall you wasted the premiums. It is your responsbility to read your insurance policy and make sure the information is correct.