In most states, you as the parent are responsible to provide his necessary living expenses. You cannot use it for things you are suppose to provide. Otherwise parents would take the children's money and there would be nothing left when they turn of age. Ssome judges allow for things like braces and etc.
You have a lawyer. They are suppose to know how to do a lawsuit. If they don't , you may want to change lawyers. These are basic lawyer issues. They should be telling you how it is done, not asking you how to do it. Sue everyone involved.
You really should get an attorney. If they do not have insurance, your insurance will compensate you just like they did. They will go after the other driver or owner. Your attorney can send them a letter and see if they have insurance.
I am very sorry for your loss. You have not really given any information as to how the accident happened, who was at fault, and if they have sufficient insurance to cover the case. You should consult an injury/wrongful death attorney before you do anything. You may have to talk to a probate attorney since a death is involved.