Is it permissible for Anwar to marry Sumaya, knowing that Anwar's grandmother (Matra) breastfed Sumaya?

If the grandmother suckles the daughter Sumayyah five full, satisfying sucklings, then Sumayyah becomes Anwar's maternal aunt through suckling, and therefore it is not permissible for him to marry her, due to the saying of the Prophet, peace and blessings be upon him: "What is forbidden by lineage is forbidden by suckling." However, if the suckling is less than five full, satisfying sucklings, then she is not forbidden to him. This prohibition applies to all of Adilah's children.