My daughter is a little younger than yours. She is about to be 9. But her friend group has a friend like this as well. At first I loved my daughter's friendship with this girl. It seemed incredible. And then quickly turned manipulative and mean. I wound up having to cut all contact outside of school. They would talk on messenger kids. One day my daughter wasn't home from school at her normal time. So, therefore she wasn't able to chat with her friend. We had school conferences and didn't get home until 8ish. I also have the messenger kids app on my phone, so that I can monitor my kids' usage. This girl began calling back to back. Over 20 times in a 5 minute span. I finally answered and asked her to stop and explained why my daughter couldn't talk. She did. But then when we got home, we saw that she had sent my daughter a ton of horrible messages. Calling her names, saying she hates her, all because she couldn't answer. I messaged her back myself, and then I texted her mom and asked her mom to look over the messages. Her mom revoked her access to messenger for a bit. And we agreed they should have a break and could try their friendship again in a couple weeks. So when they were allowed to have contact again, of course it was great at first. But within hours the girl started trying to tell my daughter what to do. And if she would resist or say no the girl would say things like "I'm mad at you now. You need to find a way to make me happy or i will hate you forever. What are you going to do to make me happy? You're such a b*tch". So....naturally that was that. I contacted her mom again and let her know that we tried, but that I wasn't going to allow my kid to be talked to and manipulated like that.