As I read it, your story added up to a bunch of Horse apples(that come out its butt)
By your meager description, some of us can relate. So we know the hoops you got to jump through...and which insurance will play a role.
As there are 2 vehicles there ain't no such thing as "Incognito" . The other person's identity is known for that is how NASTY INSURANCE COMPANIES ARE. They know who he is, whether he is covered as a sober borrower or not, and once you say he was drunk, his insurance coverage (if he had ANY) is invalid.
. There are 2 parties in this auto CRASH, Mr "I" because he did a faceplant into your son's butt, and your son (who obviously was NOT wearing his seatbelt which in some places "insurance takes a dim view to that...enough to refuse payment.).and they are within their legal right to do that...as it is written in the insurance contract the son signed.
. So if you do not know who to file with, then you are in for a world of hurt & financial ruin.
In the U.S., everyone "Lawyers up" for almost everything no matter how minor, and in this case which is major you are not Lawyering up? That is so QUAINT.
You are willing to accept all costs. Dum, dum, dum.
No, I am not going to tell you FOR EVERY CASE IS DIFFERENT.
"You know YOU are not SMART ENOUGH TO HANDLE IT YOURSELF" and just know that insurance accepts your payment much easier than you trying to get money from them. Then they got the walls STRONGER THAN FORT KNOX. Or "El Cheapo" is another term.
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