He can also go near a sister who is not married. She would have depended on him because she did not have a husband. The priest can make himself “unclean” by going near her body.
But suppose the priest’s daughter becomes a widow or is divorced. She does not have any children. And she returns to live in her father’s house, where she lived when she was young. Then she can eat her father’s food. But a person who does not belong to a priest’s family can’t eat any of it.