Ruling on one who was breastfed by a woman who had not married

Question: My wife was breastfed by my maternal aunt for two years when she was a child. At that time, the aunt was unmarried and a virgin. Later, this aunt married and became the mother of ten children. Is the aunt considered a mother to my wife through breastfeeding? If the answer is yes, must my wife observe hijab in front of the aunt’s sons because she is their mother through breastfeeding? And must the aunt’s daughters observe hijab in front of my wife’s sisters, or not?

Answer: Praise be to Allah, and may Allah send prayers and blessings upon the Messenger of Allah, upon his family and his Companions, and upon those who follow his guidance. After that:
If your maternal aunt produced clear milk for her and breastfed her, then she becomes her mother (a mother to your wife), provided she produced milk for her, even if she had not married. If she breastfed her within the first two years of her life five times or more, then she becomes her mother, and your wife becomes a sister to the aunt’s sons—a sister to all of her children, male and female—because she has become a mother through breastfeeding; therefore, all of her children are brothers to your wife.