My sister (may Allah have mercy on her) was breastfed by my paternal aunt along with my paternal cousin. The latter married my full maternal uncle and gave birth to many children. Is it permissible for me to marry her daughter?
It is permissible for you to marry the daughter of your sister's foster sister as long as the woman that breastfed them is not one of your Mahrams (spouse or unmarriageable relatives), as the girl you wish to marry is a non-Mahram.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.