M.P.
C., it's important to talk with the teacher first and if you are not satisfied go to the Vice-Principal or Principal, which ever one is assigned to behavior situations.
It is also important to keep an open mind when talking with the teacher. She will listen to you better if you listen to her first. I don't know how old your daughter is but my granddaughter is 6 and in the first grade. She's into a fantasy sort of lying stage. I have playground duty one lunch period a week and I have heard her tell an entirely different story about what we both saw.
You haven't talked to the other kid or the teacher and so you also have not heard all sides of the story. You need to know all sides before you can know what is going on.
I want to suggest a possibility of what could be going on here. I see this between kids all the time. Kid #1 does something that causes kid #2 to react by doing something to kid #1. Then kid#1 complains to the teacher. Once kids get into that cycle even they don't know what they're doing.
It would help me to be more specific if I knew the age of your daughter. Tweens and teens are even harder to understand than the little kids. They get into a lot of game playing. If these kids are game playing it is important to know why they are doing it. What do they want to achieve. Perhaps this boy really just wants the girls to pay attention to him but he doesn't know how to get their attention in a more positive way. Maybe, instead of just saying no, the girls respond in a catty or put down way when he asks. And the teacher sees this in action. I have taught. It would be rare that an experienced teacher wouldn't know the personalities and behaviors of the kids in her classroom. Of course it's possible the teacher is playing favorites and if she is she may not be aware of it. Communication is the only way to amicably solve this sort of problem.
My focus would be to find out what is happening from all view points. You could even go to school and observe. And then find a way to teach both the girls and the boy a different way of relating to each other. If they're young and both you and the teacher are on the same page this should be somewhat easy.
My parents taught me to believe that when I am in the classroom the teacher is the authority. They didn't take sides until they talked with the teacher. And even then they didn't criticize the teacher if they disagreed with what she had done or was doing. They talked with me and my teacher to find a solution that would work for them. And then I was to do what the teacher and my parents had decided to do. If that didn't work there was more talk. My mother always asked me what I wanted to accomplish and she helped me understand how that fit with their decision. When I was in junior high I would go with my mother to talk with the teacher.
M.