I started a new post as HoD and replaced a teacher who put up with a lot of problems. I taught a group of 39 Year 9s last half term and then changed the groups to balance the numbers out. While other colleagues supported, the second in department, steadfastly refused to teach the students and sent them back to me. I wrote a note to say that all colleagues must share the numbers and sent the students back. They returned and I had to make other arrangements. Having discussed the matter with her, I had informed the team via a weekly newsletter that I had taught the group for a term and that the changes would happen. She said that nobody really reads newsletters and I responded that it was a professional responsibility and that the team share it. I was told to go back to Senior Leadership to deal with it, and that she would not take any more students. I walked off then she told me that she could have two students as some had left her group. I said 3. She walked off saying 2. What should I do now?