Is it obligatory to fast for two consecutive months as a result of causing the death of one's father in a car accident in which there was shared blame?

If the driver takes all safety precautions, inspects the car, adheres to traffic rules, and is fully aware, then an accident occurs that he could not avoid, there is no blame on him, no expiation (kaffara), and no blood money (diya). However, if he neglects any of these conditions, he is liable, and expiation is incumbent upon him, and the blood money is on his 'aqila (male relatives on the father's side). If negligence occurs from both drivers or from one of them, expiation is incumbent upon both or upon the negligent one among them, and half of the blood money is on the 'aqila of each of them or the 'aqila of the negligent one among them. If no negligence occurs from either of them, there is no expiation and no blood money.