Each of them breastfed the child of the other; do any rulings result from that?

She is not permissible for him to marry because she is his maternal aunt through breastfeeding (radaa’ah)

He is married to his maternal aunt through breastfeeding

He breastfed from his maternal aunt twice; can he marry her daughter?

The blessing of natural breastfeeding

It is permissible for a woman to breastfeed her child before doing ghusl

Breastfeeding a child during pregnancy

Ruling on milk banks

The rules of Radaa’ still apply if the child drinks the breast-milk from a bottle

Is It Prohibited to Breastfeed after 2 Years in Islam?