Hi S.,
I don't know if this response will be posted, but I can make some unprofessional suggestions for your problem at this point.
Your daughter has been diagnosed with ADD. Is she taking adderol or any of the other pharmaceuticals? Alot of times ADD can be intensified from diet. Sugars, wheats, milk products, and artificial colors and ingredients are the worst. The artificial colors seem to really set my son off so that he cannot control his body or actions. There is some really great information regarding diet and the ADD connection. It's just a suggestion, but attempting to try a whole foods diet (for the whole family so that she does not feel singled out) really can help to "ground" her.
Also, there is a chance that she may be what is called an "indigo child." Often mistaken as ADD, they are headstrong and strong willed. They know their purpose when they come into this world and have direct connection to universe often times extremely intutitive. They are born with their chakra system fully functional (most of us only operate out of the seven basic ones) and have direct connection to universal flow of consciousness via the twelfth chakra (hence the name "Indigo") YOucan definitely find more information online about this and Lee Carroll has had a hand in writing a book called "Indigo Children" which is about how to understand them and how to help them through. It is diffuclt to be Indigo. There is also an incredible movie made by Neale Donald Walsh called Indigo. Most movie stores should have it.
Other than that, if you haven't already, try to become friends with her. let her know that you value her opinion with family matters. Talk with her and try to avoid talking at her. She is really needing to know that you respect her so that she can learn how to respect you. Don't count her as separate fromyour problems. That is how my mother and I made it through some very difficult times.
I send you both love and hope that anything I have said has helped. May Peace be with you and your family.