Is it permissible for a man who was breastfed by his grandmother's wife to marry a girl who was breastfed by his uncle's wife, knowing that his foster brother is this girl's paternal uncle?

If two individuals are nursed from the same breast, they become siblings through suckling (rada'a), and marriage between them or their children is prohibited. Based on this, if you were nursed by the same woman who nursed your paternal uncle, he is considered your brother through suckling. Consequently, you are not permitted to marry his suckling-daughter, as she is in the legal position of your paternal uncle's daughter by lineage. It is necessary for there to be five full, satisfying sucklings to establish the prohibition.