How is it possible to show benevolence to deceased parents and two deceased sisters who died in a car accident? Is it permissible to give charity on behalf of all of them, or only on behalf of the parents? What are the recommended acts in this regard, knowing that the deceased father had an illicit relationship?

The best things to offer the deceased are prayers for their mercy, forgiveness, and entry into Paradise, and giving charity on their behalf. Dedicating the reward of good deeds to the deceased is commendable, not obligatory. Praying for mercy for one's parents is one of their confirmed rights after their death, as Allah Almighty says: "And say, 'My Lord, have mercy upon them as they nurtured me when I was small.'" One must disregard negative talk about the father, hold a good opinion of him, conceal his faults, and frequently invoke mercy and seek forgiveness for him.