Are the brothers of the foster daughter, nursed by the first husband, considered full siblings to the grandfather's children, or only to the foster daughter? And are the brothers of the foster daughter, nursed by the second husband, considered full siblings to the grandfather's children, or only to the foster daughter? And to whom is the milk attributed in fostering, to the husband or to the wife?

If the grandmother breastfeeds two female infants five times before weaning, the grandmother becomes their foster mother through suckling, and the two infants become sisters to the grandmother's children. This is based on the Almighty's saying: (and your mothers who suckled you and your sisters from suckling) and the Prophet's (peace be upon him) saying: (What is prohibited by lineage is prohibited by suckling).

This ruling applies only to the suckling infant and their descendants (children), not to their ascendants (father and mother) or their siblings. Thus, the other siblings of the two infants have no relation to the grandmother or to your paternal uncles and aunts, because the grandmother is not their mother, neither by lineage nor by suckling.

The shared milk between a woman and a man establishes a prohibitive relationship. If the woman breastfeeds with it, she becomes a mother to the one she suckled, and her husband becomes a father to that child through suckling. The prohibition extends to the suckling child and their offspring, but it does not extend to the suckling child's siblings or to those higher in relation, such as their father, mother, paternal uncles, and paternal aunts.