Ruling on marrying the daughter of a woman from whom one’s brother nursed

Question:
My respected Shaykh, I have a brother who nursed from my cousin’s daughter. Is it permissible for me to marry the one after her, or not?

Answer:
If your brother nursed with your cousin’s daughter, meaning from her mother, then he is her brother. If he nursed from her mother a legally valid amount of five breastfeedings, or more, within the two-year period, he becomes her brother. As for you, there is no prohibition regarding her, provided you did not nurse from her mother, nor from her father’s wife, nor from her sisters. She is not prohibited for you; she is prohibited only for him. This applies to her, the one before her, and the one after her.
The prohibition is specific to your brother if he nursed from her mother five breastfeedings, or more, in which case he becomes her brother, and she becomes prohibited for him, along with all the daughters of the nursing mother and all the daughters of the husband who provided the milk. They are his sisters, provided his nursing included five breastfeedings, or more, while he was a small child within the two-year period. As for you, there is no blame on you.