Thank you for writing. As you guess, the most important problem is not the stealing. The most important problem is that this child feels unloved by her own mother. From your niece’s point of view, her mother has abandoned her several times and replaced her with other children. Of course she is jealous of her siblings! Her mother loves them and doesn’t love her.
Your niece is not a kleptomaniac. She is a child who is deeply hurt. Like many children in her situation, she can’t talk it out so she acts it out. It may be that she feels her mother has been stolen away from her so now she is stealing from other people. On top of that, this little girl may feel defective because she has a learning disability that makes it hard for her to do well in school. Her conclusion may be that she in unlovable. Please understand that this isn’t a conscious decision on her part. Kids who can’t express their pain often act it out.
Your sister doesn’t have positive feelings for her daughter for reasons we don’t understand. It’s unlikely that she will change so it is up to you and your mother to help this little girl feel lovable and capable.
You and your mother have provided a home, support for her school difficulties and love. None the less, she may believe that her time with you is limited. Perhaps it’s time for you and your mom to talk with her about how much she means to you and to reassure her that she has a permanent home with you. Catch her being good and right as much as you can. She needs the emphasis to be on what is right about her, not what is wrong. Give her lots of positive comments and hugs whenever she is doing the right thing. My guess is she is doing fine many times in a day and deserves many hugs. Let her know she can come to you with her troubles and that you will do your best to comfort her, even though you may not be able to fix it.
The stealing can’t be ignored but it needs to be addressed from a position of sympathy, not anger. Let her know that you understand that she hurts but that the solution is not to hurt the people who love her. Ask her if she can talk about her feelings with you. Reassure her that you aren’t going to abandon her as her mother did, even if she makes some mistakes. People who love each other forgive each other and figure out how to make sure the problem doesn’t happen again. Then talk to her about what she needs so she doesn’t have to steal.
This is a very important time in your niece’s development. Separating from the adults is a normal part of becoming an adolescent. But she doesn’t have the inner security to do that well. Please use the next year or two to put extra effort into helping her feel that she is worthwhile and worth love so she doesn’t go looking for it in the wrong places.
You’ve already done a great deal. Your niece is lucky indeed to have you and your mother. I hope you can continue to provide the love and guidance she needs.
I wish you well.