Under NY law, the car that stuck you in the rear is presumed negligent and will have to give a non-negligent explanation for why the accident took place. The most often given is the car in front made a short or sudden stop. Judges usually reject that defense. Another popular (and more successful) one is that the lead car suddenly changed lanes directly in front of the car causing it to rear-end the lead car.
It is not too late to hire a private lawyer. Private lawyers such as myself carry a much smaller case load so we have more time to devote to the client and their case. I handle cases like yours all the time.
It depends what County you are in. In Queens for example the DA wil not make an offer after indictment. In other places offers can get wrose or get better as the case moves along... it often has to do with the strength of the DA's case.
It doesnt matter what she thinks. She must tell the kids where the will is. If she doens't, under the Surrogates Court Procedures Act, the kids may summon and examine the Court can order her to give the information. If she refuses, she can be held in Contempt of Court and perhaps jailed.