Is it permissible to marry the sister of the daughter of the maternal uncle, from whom the questioner suckled more than 10 satiating breastfeeds, knowing that there is a son between the two sisters, and do medical analyses have a ruling in this regard?

If the questioner and the girl were nursed by her mother five or more times within the first two years of life, then her mother becomes his wet nurse, and it becomes forbidden for him to marry any of her daughters, as Allah Almighty says: "and your mothers who suckled you, and your foster-sisters" [An-Nisa 4:23], and as the Prophet, peace and blessings be upon him, said: "What is forbidden by lineage is also forbidden by fosterage." However, if the nursing was from another woman, then the ruling does not extend to her other sisters. And laboratory analyses are irrelevant as long as the nursing is established Islamically.