Is expiation for accidental killing obligatory upon the deceased person who caused an accident that led to his death and the death of his friend, especially since the family of the second deceased person has waived their right to blood money?

It was previously clarified that if a driver takes all safety precautions and is not negligent, yet an accident occurs resulting in a person's death, then neither expiatory payment (kaffarah (definition)) nor blood money (diyah) is due from him, because there is no liability for what cannot be avoided. However, in the case of the driver's negligence, the blood money is incumbent upon his 'Aqilah (male relatives on his father's side), and the expiatory payment for accidental killing is also due. If he dies in the accident, the expiatory payment is to be taken from his estate.