out of control!

Ok, this is a little long, but I pray some one will take the time to read this and offer some help.

I have a 10 year old step-daughter who is defiant beyond comprehension. She is extremely smart, yet deceitful, dishonest, hateful, and manipulative. I will try to summarize her behaviors as much as possible.

At school:
Screams, yells, has fits in the classroom
Follows teacher around yelling at her
Disrupts class numerous times daily
Refuses to go to principles office
Has had to be physically removed from class more than once
Has grabbed teacher, not allowing her to call office for help
Slapped a girl in the face on the bus
Says hateful things to teacher and principle, i.e., I hate you, You are the worst principle/teacher ever, You have no right being around children
Has graffitied the bathroom stalls with same hateful messages

At home:
Lies daily, about EVERYTHING
Tells mother, father, and myself that we abuse her
Tells all of us we are the worst parents, we have no right being parents, she hates us, she wished we were dead
Has screaming tantrums that can last for hours
Talks to us with the worst attitude I have ever seen, with the most hateful look in her eyes
Is so volatile, she upsets the baby and we can't calm the baby down
Writes how much she hates the baby
Has, in the past, hit us
Kicked me in the stomach while I was pregnant, hard enough to knock me to the ground, and has never shown remorse for it
Rubs and scratches herself and says we are abusing her
If we try to physically pick her up to take her to her room, she flails and screams at the top of her lungs that we are killing her and abusing her
Has hurt the dogs when she is angry
Has slapped me across the face
Has hit her mother on numerous occasions

What we have tried:
Strict punishments
Talking about her feelings/why she is so angry
Positive reinforcement for EVERY little thing we see her do good
Star chart system
Earned allowence
We also make sure she gets PLENTY of attention as to not feel jealous of the baby
All of us do one-on-one special days and activities with her, but it is never enough

Counseling:
She was admitted last year to a psychiactric facility for 2 weeks, 24/7 observation. She was as good s gold, and they could see nothing wrong. She can control it when she needs to
Has been in counseling for 2 years. Is never honest, plays victim role ALWAYS. Knows how to act in front of counselor so she looks like it is out of her control, or it is not her fault.
Tells counselor and school she is abused, which she is NOT. WE are the ones being abused.

We have tried walking away and locking ourselves in our room. She will just pound the door for hours, screaming. This child wants for nothing, but is never happy with what she has. And always, the first half of the school year she is a straight A student with no problems. As soon as she gets comfortable, all hell breaks loose. If you watch her with other kids unnoticed, she is mean and bossy, but if she knows you are there, her behavior is completely different. When she is caught in a lie, with 100% proof, she still will not admit to it. If we enforce a punishment because of her behavior, it is our fault she is unhappy, bored, or sad, not her own. This child could not accept consequences if her life depended on it. We don't know what to do!

I have searched the internet, but can find no resources to help my situation. Just everything about abused children, not abusive children. Now that my husband and I have a baby, we fear for her safety, and the influence my step-daughter will have. Our house is turned upside down. We work side by side with her birth mother, and we all try to tackle this together. I don't think my step-daughter has gotten worse over the years, she is just getting older and learning more hateful things to say and more deceitful things to do.

Are there resources to help us? What are the laws regarding this? If she has one of her meltdowns with me and the baby in the home, can I legally call the police, and will they help me?

And yes, she is on medication. The dosage has been upped twice, but no change. PLEASE HELP!! This child is out of control!

This child needs help! Someone who knows how to treat manipulative kids!