A woman who took care of a child does not replace his/her biological mother
4-1-2010 | IslamWeb
Question:
assalam alykum i hav given my daughter to my sister in law now the daugter is 13 years old now she doesnt allow me to show love to her or allow us to talk to the child she says that u have given now ur relation is finished that giel is getting attached to me due to the miss behavior of her fostr mother and getting spoiled do i hav any right over that girl can i guide her pleez help and sugest in light of quaran and sunnah
Answer:
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 
is His slave and Messenger.
This girl is your daughter and you are her mother, so you have rights on her as any mother has rights on her children that they should be kind and dutiful to you. The fact that you gave your daughter to your sister-in-law to nurture her does not change the reality and that woman does not become her mother due to that. Moreover, it is not permissible for this daughter to be traced back to that woman or her husband as this is adoption and this is forbidden in Islam. For more benefit, please refer to Fataawa 86418 and 88415.
Moreover, that woman has no right to prevent you from talking to your daughter or from expressing your affection to her. The fact that you had given your daughter to her does not mean that you would not have any relation with her.
In addition, if that woman is not nurturing this girl in a proper manner, then you should not give your daughter to her. Furthermore, if she mistreats your daughter, it is not permissible to leave her with her as she will be harmed by her. The age that this girl has reached makes it an obligation that she be in a house where she is safe from any corruption.
Allaah Knows best.