I am a non exempt Administrative Assistant and my employer has assigned the other Administrative Assistants under my supervision. My title specifically states that my position does not supervise. I am also being rated on the performance of the other Admin

My position is non exempt Admin Asst III. My job description states does not supervise others. My employer is making me supervise 3 other non exempt position employees (receptionist, an Admin Asst. III same as me, and the other is a clerical position. I also have to write their performance reviews. My performance review is being rated in one of the sections on the performance of the others I am supervising. We all have a Manager that oversees all four of us and he gives the final approval on all of our reviews. I stated I did not want to supervise, but they refuse to change it. The previous person that used to perform this task was an exempt position of Office Services Manager. They will not give me that title. I had called HR this, but nothing got resolved. They claim they are training me for Management. Can they force me to perform these tasks without a promotion to an exempt position?