Financial Channel

I'm in CA. A friend of a family was paid to drive my car back from an airport. On a way to my house, on a highway, he lost control and crashed it. He wouldn't provide me with his insurance info and much later said that he changed companies and didn't have an insurance at the time of an accident.
My insurance send me a letter asking: to provide them with proof of his insurance, or he'll be added to my policy, or I have to sign and mail an Exclusion Form within 14 days of the inception date of the policy (my policy started on 9/7/2005, what does it mean to me? am I loosing any rights if I sign this exclusion and later file in court against him?
He's working and drives his own car every day, I'm sure he has insurance, but I don't know where and how to get this information.
Please help me with an advice and let me know if it is ok and safe for me to sign this Exclusion. The language used on this Exclusion Form is very complicated and it says: This endorsement changes the policy. Please read it carefully. This exclusion is applicable to this policy, all future renewals...
The form is PA CA 20 08 04
Thank you!

If you sue him, you should be able to make him disclose his history of insurance coverage at or around the time of the accident. If you are confused about the legal effect of any particular form from the insurance company, have it reviewed by a lawyer.