She wants to raise an illegitimate child with her sons

Dear Brothers & Sisters,
As-Salaamu-Alaikum wa Rahmatullahi wa Barakatuh. (May Allah's Peace, Mercy and Blessings be upon all of you)
One of our brothers/sisters has asked this question:
In the event that a sister dies leaving a female child, who has no other muslim relatives and father has no rights because child was born out of wedlock, although the mother of this child, became muslim.
Is it permissable for a married sister with all sons to care for the child as her own, with the approval of her husband.
(There may be some grammatical and spelling errors in the above statement. The forum does not change anything from questions, comments and statements received from our readers for circulation in confidentiality.)
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Answer:
Praise be to Allaah.

This child is illegitimate, i.e., the child of zina (adultery/fornication), and as such comes under the rulings on foundlings (laqeet), so long as his or her mother has died. It is a form of kindness to this child to keep him and look after him. If the Muslim sister takes this child in with her own children and brings him up, this is an act of kindness and a righteous deed, but he will not be counted as one of her children or one of her husband’s children, rather he will be a stranger (ajnabi), unless she breastfeeds him, giving him five complete feedings, whilst he is still an infant; in that case he will become a son to her through radaa’ah (breastfeeding) and a son to her husband through radaa’ah. Her sons will also be brothers to him through radaa’ah, but there will be no rights of inheritance between them, because the relationship between them will be one of having been raised together and of kindness, or of brotherhood through radaa’ah, none of which bestows rights of inheritance between them and this child. 

Whatever written of Truth and benefit is only due to Allah's Assistance and Guidance, and whatever of error is of me. Allah Alone Knows Best and He is the Only Source of Strength.
Your brother and well wisher in Islam

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