Permissibility of a son making Kaffarah on behalf of the deceased father

Q: May Allah reward you with the best. Allah predestined that my father had an accident while driving his car, which resulted in the death of one person in the car that my father collided with. As for my father, he broke his leg and remained in the hospital for two months before meeting his Lord. My question, may Allah reward you with the best and have mercy upon your parents, is: Should my father have observed fasting or not? If he was obliged to observe fasting, is it permissible for one of his children to make up for this fasting or pay a Kaffarah (expiation) on his behalf?

A: If it was your father who caused the accident or was a participant in it, it is obligatory for him to offer a Kaffarah (expiation) for involuntary manslaughter, which is emancipating a believing soul. If he cannot afford this, he should fast for two consecutive months. In this case, it is Mustahab (desirable) that one of his heirs should observe fasting on his behalf because it is authentically proven that the Prophet (peace be upon him) said: If anyone dies in a state (that he had to complete) some days of fast, his heir must fast on his behalf. May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.