If you don't mind her being in the back, it's OK. But if you prefer to be in the front sometimes, just slowly work up the line.
If the trail is wide enough (or just practice in an arena) then start walking next to the horse in front of her. Slwoly just work your way so you are in front of that horse. Then walk like that for a few days. If you still want to bw head more, just do the same thing. I think that maybe you should walk next to the lead horse for a while, then when she seems OK with that, work your way up ahead of her. If she stops, just ask her to go and don't let the other horses pass you. My horse can be the same way. He would rather follow Brisco than be behind him. I made Golley get ahead of Brisco and walk. The first few times he wouldn't go, but when I wouldn't stop asking, he would walk forward - only to turn around and walk to brisco. So when he turned, I just kept turning him until he was walking away from Brisco again.
So I have found that it works, just take your time and don't rush. But if you don't mind being in the back, I wouldn't worry about it. There isn't a big need to be in the front, unless you want to! Haha!!
Hope this helped!