Hello. My husband and I are planning to adopt a daughter, we already have a biological son who is 21 months old. I was unable to breastfeed my own son because I do not produce enough milk, so I doubt that I will be able to personally breastfeed the adopted child. So how else can I manage the Mahram (permanently unmarriageable) issue? Can I have my sister-in-law (husband's brother's wife) breastfeed my son and later breastfeed the adopted child so that they are both milk siblings and she would thus become my husband's niece? In this case, would expressed breast milk work or does she have to actually physically breast feed him? Also, we will not be giving the adopted child our names in official and legal documents, but is it ok if we keep it a secret from her and agree with everyone else on the same until she is mature enough to comprehend that, or do we have to tell her that she is not our own? Thank you.

All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger. 

If the girl whom you want to join to your family has not yet reached the age of two, then you can have your sister-in-law (the wife of your husband's brother) breastfeed her and your son five times, whether directly by physically breastfeeding them or by pumping her milk in a bottle or so and then feeding it to each of them five separate times. Accordingly, the girl becomes your son's sister through breastfeeding, and your husband becomes her paternal uncle through breastfeeding.

There is no religious impediment to delay informing the girl about the truth about her lineage until she grows up and becomes able to comprehend the situation. Please, refer to fataawa 84422 and 82371.

Allaah knows best.