Ruling on marrying a woman whose brother was breastfed by the suitor's mother

Question:
This is a letter we received from Riyadh from the sender (M. A. J.), in which he says: I have a cousin, and I want to marry her, but I am concerned about it because her brother—older than she is—was breastfed along with my sister, who is younger than me. Is she permissible for me? And are my sisters permissible for my cousin's sons?
And thank you.

Answer:
As for her, she is permissible for you; because the breastfeeding of her brother by your mother does not harm, the breastfeeding of her brother by your mother does not harm, and it does not make her forbidden to you, so she is permissible for you. As for him, if it was a legally valid breastfeeding, meaning that it was five feedings.
As for him, his breastfeeding is examined; if it was five feedings or more within the two-year period, he becomes your brother, he becomes your brother and your brothers' brother, and he becomes the paternal uncle of your daughters, so none of them is permissible for him.
As for if his breastfeeding was less than five feedings, then he does not become your brother, or if the breastfeeding was not within the two-year period and he was older, he does not become your brother. If the breastfeeding was five feedings, or more, within the two-year period, then he becomes your brother and the paternal uncle of your daughters and your brothers' daughters, and it is not permissible for him to marry any of them. Yes.