Is it permissible for my brother's wife to breastfeed my child—who is one year and three months old and does not rely solely on milk for his nutrition—and her daughter, so that they become siblings through رضاعة (radha’a, suckling/nursing), and what is the ruling according to the Hanbali school of thought?

Mahaarim (prohibition of marriage) through fosterage is established upon the fulfillment of two conditions:

1. Five Fosterage Sucklings: There must be five or more fosterage sucklings. This means the child latches onto the breast, sucks the milk, and then releases it voluntarily. As a precaution, each suckling should occur in a separate session. 2. Fosterage within the First Two Years: The fosterage must occur within the first two years of the child's life. This is the period during which milk is the primary nourishment for the child. Hence, "suckling is from hunger," meaning the prohibition is established if the suckling child is an infant whose hunger is satisfied by the milk.