A person wants to marry his cousin,

Q: A boy and girl were breastfed together when they were babies, is it permissible for his elder brother to marry this girl?

A: If the case is as you have described, it is permissible for the elder brother to marry this girl as this breastfeeding does not affect the marriage.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.