Marrying his wife's sister by breastfeeding

Q: My wife has a milk-sister whose husband died leaving her with five young orphans. I want to marry her to become a guardian to the orphaned children, so I can support and clothe them. Is it permissible for me to marry her or not? A: If it is confirmed that this woman is your wife’s sister through breastfeeding, it is not permissible for you to be married to two sisters at the same time, because Allah (Exalted be He) says: Forbidden to you (for marriage) are: your mothers, your daughters to His Saying: ...and two sisters in wedlock at the same time, except for what has already passed It is also authentically reported from the Prophet (peace be upon him) that he said, “Breastfeeding prohibits what birth (consanguinity) prohibits.” In regard to her orphaned children, you can be a guardian to them and support them without marrying their mother or being in Khulwah (being alone with a member of the opposite sex) with her. (Part No. 21; Page No. 121

A: If it is confirmed that this woman is your wife’s sister through breastfeeding, it is not permissible for you to be married to two sisters at the same time, because Allah (Exalted be He) says: Forbidden to you (for marriage) are: your mothers, your daughters to His Saying: ...and two sisters in wedlock at the same time, except for what has already passed It is also authentically reported from the Prophet (peace be upon him) that he said, “Breastfeeding prohibits what birth (consanguinity) prohibits.” In regard to her orphaned children, you can be a guardian to them and support them without marrying their mother or being in Khulwah (being alone with a member of the opposite sex) with her. (Part No. 21; Page No. 121) By supporting them, you could hope for Allah’s Reward. Otherwise, you may refer them to those in authority for them to manage their affairs in the way that they can with social insurance or let the children go to an orphanage or somewhere similar.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.