Anandi brought back her daughter along with her.
She was in no position to tell that child that she is her mother because she hates her mother and doesn't want anything to do with her mother.
If the child doesn't want to meet her mother no one can force her. Anandi cannot force the child to meet her and listen to what she has got to say because the child has suffered too much and been through a lot and holds her mother responsible for her sufferings.So negativity in that child's mild is because of the garbage bin story as well as sufferings.
So the only thing is slowly prepare the child to make her want to listen to what her mother got to say.
Slowly the child because of seeing Anandi and Shivam as well as what that girl Chakor told about mothers her anger came down a lot and she wanted to meet her mother. But unfortunately the mother did not know that her child is ready to meet her because Mangala made sure that Anandi never got to know about Nandini wanting to meet her mother.
So Mangala brought this new mother and made sure that the child went back to being angry with her mother.
Even Amol did not want to meet his parents when they came searching for him.Because he too was told that he is left in orphanage because of his physical disability.
Anandi did convince him but the parents realised that he was not ready to accept them so they went away.Amol later on went to his parents place and then after getting to know them well enough he went back to them on his own
That's how it should have been in Nandini's case too the foster mother or self proclaimed mother should have told that her mother had come to meet her and then let the child decide.
Here the child's mind has been spoilt by the so called mother of the child who can only keep the child with her by feeding the anger the child has against her own mother.
When the child is heart broken like she is now it is quite understandable that she is behaving in this manner.