The Magical Peoplez

Rachel has a big group of friends. There is her, her sister Ashley, Kristen, Cassandra (Cass), Ella, Ariel, Christine, Luna, Brianna, Katy, Sadie, and Alissa. One day after school, the are all climbing a tree, and they climb into a magical world.
A new girl moves to their school named Terra. No matter how nice Rachel and her friends are to her, she is still really mean to them.
How are these two things related to ask? That is a mystery that will be solved if you read this.