Is it permissible for the son of Ahmad to marry Su'ad, daughter of Al-Hasan, if the mother of the son of Ahmad breastfed Al-Hasan when she was married to the paternal uncle of the son of Ahmad?

Whoever was suckled by your mother five times becomes your brother through breastfeeding (radha'a), and his daughter is considered your niece through breastfeeding. Marriage to a niece through breastfeeding is forbidden, due to the saying of the Prophet, peace and blessings be upon him: "What is forbidden by lineage is also forbidden by breastfeeding."