Sorry to hear about this. A bad way to start your day. It sounds like the accident happened on a public street. If this was something that happened in Wisconsin I'd say that the laws that relate to the maintenance of streets and public areas are such that there is probably no ability to recover from the municipality for improper maintenance/salting of the roads. If the accident happened on private property you should talk to a local attorney about whether there are any local codes/laws...
I'd recommend sending a direct question to an attorney via Avvo. Or sit down with someone next week. I don't think it is as easy as you'd like it to be. Remember DOC staff are not attorneys they may be trying to be difficult for no other reason.
Do you know which case it involves? If there is already a judge assigned you may want to have your attorney contact the judge. I'd strongly recommend contacting an attorney and have your attorney accept service on your behalf.
Is that the only mistake? You can talk with a local attorney and get their opinion but I think the other answer is probably correct. You also probably signed a document that said that you reviewed all of the documents and that they are correct and accurate.
I tend to agree with the other attorneys who answered this question. Sometimes it is just best to walk away and avoid the conflict. If you had standing to sue and you did, in fact, sue you would probably see Aderia and Jasmine again at a court appearance and deposition. Do you want to see them again? Sometimes bad things happen to good people. It takes a wise person to walk away.
The facts as of moment of the collision are most important. If he comes to live with you now or a year from now should not have an affect on the investigation. Are you worried that the insurance company will deny coverage? Was he a permissive user of your car the day of the collision? There are a lot of questions. I'd recommend you speak with an attorney about this. Especially, if your son was not at fault in the collision and the insurance is questioning whether coverage would apply.
I agree with Jason that the Wisconsin Bar Association may be a good resource. Also, did you meet with an associate or the owner? You may want to call the attorney's supervisor and see why they billed you without fully explaining the fee situation.
Do you in which state he has a drivers license? In Wisconsin if you cause a collision and have no insurance the DMV can take away your license until you pay for the damage. You may want to call the equivalent of the DMV in his state and ask if there is a similar procedure. The police may also be able to give you some guidance with this tactic. Good luck!