The ruling on the marriage of an infant to the daughter of a wet nurse

Question:
I am his wife. We have four children, the oldest of whom is over four years old. He was breastfed more than five times. This child has grown up and had a son. I am asking because his daughter came to me. The question is: Is it permissible for my infant son, who was breastfed by me, to marry her daughter?

Answer:
This breastfeeding has no effect. The breastfeeding that has an effect is within the first two years, before weaning. However, there is a doubt (shubhah) regarding his marriage, or rather, it is better not to marry them. This is because some scholars have not considered major breastfeeding (breastfeeding after two years) to be valid. Therefore, it is better to be cautious here and not marry them, as this is the safest course and furthest from doubt. This type of breastfeeding only occurs within the first two years. There is no breastfeeding effect if it is less than that, and there is no breastfeeding effect except within the first two years.