Since it is the parent group, there must be group rules. You can write on the group announcement that you are in the parent group, no chatting, no negative energy videos. Because the parent group is a platform for parents and teachers to share their classmates' study and homework, it is the first task to stop chatting.

Parents are convenient for teachers to publish, share and communicate; Secondly, it is also convenient for parents to know more about students' study, life and activities at school. The significance and value of parents' group is like building a rainbow bridge between home and school. Once the purpose is clear, the corresponding group rules can be generated, and in the process of interacting with parents, the tacit understanding can be reached continuously.

The above is my opinion, I hope it will help you.