Re: Children lying.
There is fibbing and then there is lying.
As an outsider - there is little you can do to make a difference if parents don't step in.
You have to confront the lie, ask her why she said that and tell her the consequences of lying.
For instance - if you see her skipping pages in the Quran. confront her - I saw you do it and you have to press that matter. There needs to be some consequence of her lying - otherwise she'll continue to do it.