Is it permissible to marry the daughters of maternal half-sisters if the grandmother breastfed one of the sons and the mother breastfed her full brother along with her son?

Suckling establishes the same prohibitions as lineage, for the Prophet, peace and blessings be upon him, said: "What is prohibited by lineage is prohibited by suckling." So, whoever suckles from a woman becomes a child to her and to her husband, the owner of the milk. This applies specifically to the suckling individual.

Your grandmother suckling your brother, or your mother suckling her brother, does not prevent your marriage to your maternal aunts' daughters, if they did not suckle from your mother or grandmother, and you did not suckle from their mother or grandmother, and no other prohibitive cause of consanguinity is established.

The suckling that prohibits marriage consists of five satisfying sucklings during the first two years of life, according to the preponderant opinion.