Some children are just horrible. They grown into horrible teens and then into horrible adults. Some people never grow out of Horrible.
Unfortunately, girls are far worse than boys in their exclusionary and targeting behaviour towards their peers.
I work in schools and have spent time in single-sex schools and without a shadow of a doubt the bullying in the girls school is absolutely some of the worst I have ever seen. The psychological effects on the victims are horrendous, but students are unwilling to report it due to the worry of the bullying escalating or being seen as a “snitch”. I’m sure many parents have heard the mantra “snitches get stitches” from their DC.
I have a friend whose daughter, let’s call her Amy, who in currently in Y13, she has been remote learning for most of this school year as she was/is being bullied relentlessly by another girl in her year group. It was both physical and emotional bullying, attacks on SM etc.
Nothing has been done about tackling the bullying and I’m guessing it was easier for the school to agree to Amy home schooling than to deal with the actual bully, who is no doubt bullying someone else right now.
OP, you must report every instance of bullying to the school. Schools love to stick their heads in the sand where bullying is concerned and tell themselves they don’t have a bullying problem. Individual acts will be seen as ‘disagreements’ but if there is continued and repeated acts, they have a duty of safety to your daughter.
Email them every time something happens, so you have a record. If you know who the bullies are, name them. Speak to the class teacher and/or Head, don’t let them fob you off with a resolution of ‘We’ll keep an eye on DD’.