What is the relationship between a son and a sister through breastfeeding, and does the wife become a محرم to everyone?

Whoever's suckling of an infant is established becomes a mother to him through suckling, and he becomes a suckling brother to all her children. This is indicated by the generality of Allah's Almighty saying: "And your mothers who have suckled you, and your sisters through suckling" [An-Nisa:23]. Accordingly, your eldest son is a suckling brother to all your sister's children, and your sister's young son is a suckling brother to all your children. Your wife becomes a suckling mother only to the child she suckled, while the rest of his siblings are strangers to her, and she must observe hijab in front of them.