Marriage to a woman who is related to you by breastfeeding from a relative’s wife

Question:
I was breastfed by the wife of my maternal uncle, Nuur al-Din. Is it permissible for me to marry my maternal uncle’s daughter from his second wife? Please note that the aforementioned daughter of my maternal uncle is Nuur al-Din’s sister on her father’s side. I ask for your guidance in this matter. May Allah preserve you?

Answer:
Yes. If you were breastfed by a man’s wife, whether the milk was pure or mixed, and if the man’s wife breastfed you completely—meaning you were breastfed within the first two years—then that man becomes your father through breastfeeding. And all of his children, both daughters and sons, become your brothers and sisters through breastfeeding from all his wives: from the wife who breastfed you and from his other wives, all of their children are your brothers and sisters through breastfeeding. Yes. If you propose to your father, he becomes your paternal uncle through breastfeeding. If you are breastfed by a woman, yes, it is possible for you to become her son through lineage and her son through breastfeeding. Yes.