Is it permissible to marry the daughter of the paternal aunt if the paternal aunt is the father's sister from his first wife, while the suckling occurred from the paternal uncle of the father from his second wife?

Fosterage establishes the same prohibitions (of marriage) as lineage, based on the Prophet's (peace be upon him) saying: "What is prohibited by lineage is prohibited by fosterage." Thus, whoever is suckled by a woman becomes a child to her and to her husband, the owner of the milk. Accordingly, if you were suckled from your grandfather's milk, you are a foster sister to your paternal aunt, and therefore, her son (your cousin) is not permitted to marry you because you would be his foster maternal aunt. The fosterage that establishes prohibition must consist of five full, satisfying sucklings.