A:
If the case is as you have mentioned, it is permissible for you to marry the daughter of your paternal aunt's son. Her father and paternal uncles being breastfed by your paternal aunt has nothing to do with the permissibility or impermissibility of your marrying each other. The same applies to your brother and sisters being breastfed by your paternal aunt; or your brother and the girl and her siblings being breastfed by your paternal aunt. Similarly, the paternal uncle and aunt of the girl being breastfed by either your mother or the mother of the girl has nothing to do with the permissibility or impermissibility of your marrying each other.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.