She is with another heifer and my 4-H steer, but he is smaller than her. I am not currently showing her, she is not even mine. I am leasing her from someone to show. I don't think she is underweight,
If you have a show stick smack him on the nose with it if he tries to run.
If you put an extra halter on him and have someone stronger than you walk on the other side with you, it might help. I have had to do that before