Legal Question in Personal Injury in California

First of all, tend to your own business and let Your Friend seek her own legal help. I don't understand the facts as you've phrased them: Why on earth did they pay the guy who hit them? If they did pay him, they have settled his claim once and for all and his lawsuit should fail. His big lawsuit will also likely fail because he was uninsured. But why aren't they suing him?

When things get that complicated then you need to let the courts handle the dispute. I am sure that it is going to be a small claims case if it ever goes anywhere so just let the other driver file the lawsuit in small claims and go to court. It will all get settled before the trial or the judge will issue a decision after a short trial and that will be the end of it. There are many more important things to worry about than a minor fender bender. By the way, never pay anyone anything to settle a dispute without putting it in writing and just stating that the payment is intended to settle all claims or damages.