What is the ruling when a man is married to three sisters, and the older sister nurses the first younger sister, and then the older sister nurses the second younger sister?
General Chapter
Al-Mughni
Book of Fosterage (Breastfeeding)
Primary text
If the older sister nurses the first younger sister, her marriage is dissolved. If she subsequently nurses the second younger sister after the first dissolution, the marriage of the second younger sister is established because her nursing did not coincide with the joining prohibition in marriage. If the older sister nurses one sister individually, and then nurses two others simultaneously (by letting them suckle together or by feeding them milk mixed in a container), the marriage contracts of all three are dissolved because they all become sisters in his marriage. He may marry whomever he wishes of the younger two because their prohibition is one of joining, not perpetual, as they are step-daughters whose mother was not consummated.
Supporting text
According to the alternative narration, when the older sister nurses the first, the marriage contracts of the first and the older sister are dissolved because the older sister becomes her mother. When she then nurses the second, her marriage is not dissolved because she is alone in the nursing relationship within the marriage. When she nurses the third, the two younger ones become sisters, and their marriage contracts are dissolved. If consummation occurred with the older sister, all become perpetually prohibited because they are step-daughters whose mother was consummated.