This was an Arab custom that they would send their young kids for nursing. The women who would breastfeed the kids would have a relation called 'Milk kinship'. In some of the articles, I've read a word 'milk-brother' for the two kids, one who is biologically the son of the woman who breastfed the other who's not biologically her kids. Is it a right use?
milk-son
milk-mother
milk- brother
milk-sib