Since the behavior is taking place at school, it is very important to work with your daughters’ teachers, the principal and/or the guidance counselor. There should be on-going intervention from the school to put a stop to all forms of bullying. Most schools have an anti-bullying program in place which is presented to students of all ages. If your school is not motivated to work with your daughters and the other children, then you can take it to the next level and speak to the school’s district administrator about your concerns.
You should reinforce at home what the school teaches: that put-downs and bullying are not acceptable. You did not mention the ages of your daughters, but you can give age appropriate consequences if they treat anyone in your home disrespectfully or hit one another. You can also encourage good behavior by having them earn all or most of their privileges. For example, points can be earned through weekly or daily chores, using positive language in and out of the home, and following directions.
You should check in with the parent of the child who has been getting hit by your daughters. Let the parent know that you are sorry about what has been happening, and that you are working on changing your daughters’ behavior. If the school has not done so already, have your daughters write a heartfelt apology letter to the girl.
Hopefully over time your daughters will see how their positive behaviors at school and at home will help their lives run smoother. They will feel better about themselves when they treat others with kindness and respect.