Roxanne is the youngest and she is a little on the small side so she suffers from small horse syndrome. I had to put her and her mother in a separate pen because she didn't want to play with the other babies, she wanted to just kick and bite them. She would run up and down the fence with them and pin back her ears when they tried to get too close. After about a month I moved them in with the other two mares and babies. I took all of them and moved them to a new larger pen so no one would try to defend their territory. I find that easier then to move a horse into a established pen. They are all so busy checking out the new area they don't target the new horse. It also helps to have them close together for a while as neighbors before turning them out together. I find they don't challenge as much and more less settle into a pecking order without too much kicking and chasing. Roxanne would even challenge the person feeding, we corrected her like her mama would. She is finally getting a little friendly, as long as you scratch her butt.