Foster Daighter trying to get case worker to back her...

My foster/soon to be adoptive daughter (age 8) is a bit too savvy on working the system to get what she wants. Last weekend we went to my grown daughters college graduation. We went to the store and picked out a special dress for the occasion. She really wanted something more ( for lack of a better word) trashy. I found something cute and age appropriate for her. She wanted tight black and pink animal print...or anything like that. I told her no, that it was an outdoor event, and that a cotton summer dress would be more appropriate. Ive seen pictures of her with her Bio Mom, and this was how they dressed together. So I do understand where shes coming from. Today the social worker came by to check on us so she could make a recommendation to the Judge for the 2.6 hearing (TPR) in June. The Kids Social Worker is coming by on Wed for the same thing. The kids told her they loved us and wanted us to be their parents :) Our social worker said she is recommending permanency for us. So, today Foster daughter said she asked my Social worker if she could chose her own clothes. She said the social worker said it was her decision what to where, and used this to try and force me to buy her things she liked. I told her "No"...I do not agree with that. She then said that My Social worker was "the boss of me" and said I had to do what she said. Again, I said "No, we were partners in doing what was best for her, and that when it comes down to it, Im her Mother. and get to make the decisions." She was very put out. I did leave a message for my social worker. Im worried that shes trying to manipulate me and others by using the system. She has also alluded to me "going to jail" if I ever raised a hand to her (which I would never do, so I dont know why she would even say that). Also, she also told my brother whom she adores, while they were rough housing...being goofy, that he had to be careful where he touched her because she would tell and he would go to jail. At this point, he stopped playing with her because he was worried what she was up to. Im a little concerned. I dont know quite how to handle her threatening to "tattle" on me when Im not doing anything wrong... Anyone out there have any input on this?? Other than that, things are going great! We just got back from a long motorhome trip with five adults, two kids and two dogs. They traveled great! Tam