Good question.

I think you'd better settle by getting whatever they are offering. I am not sure which state you are in, but it is questionable whether you can sue a minor. In addition, you cannot sue the parents as they did not harm your son in any way. Don't wait until they get smart (meaning they won't pay you anything). Get whatever you can now. When they get smart, they tell you that they won't pay for anything, what can you do?