Q. Is there a specific amount of milk that a baby needs to drink to become a foster child? Can a baby drink expressed milk to become a foster child? What relationship is established afterwards?
A. The required amount to establish a foster relationship (Radhaa’at) is that a child is breastfed to the extent that the milk is swallowed and reaches the stomach during the period of breastfeeding i.e. two lunar years. This may be achieved by breastfeeding the child with one or two feedings.
The child may suckle directly from the breast or the milk may be expressed and fed to the child. In both instances, the foster relationship (Radhaa’at) will be established.
Once the foster relationship is established, the child is considered as a foster son/daughter/brother/sister and the relationship of Mahrams (non-strangers) is established between them. Accordingly, they can never marry each other and therefore, do not have to observe hijaab from each other on attaining buloogh (maturity). However, a foster child will not inherit from the foster parents but will inherit from their biological parents. (Hindiyyah 1/342)
Allah Ta’ala Knows Best
Mufti Ismaeel Bassa