Hahaha I answered this in the same post somewhere else.
She sounds like a very green horse. I went through this with my 3 year old when
I was starting him. First things first.....LOSE THE ROPES. You can't force the horse to take the bit, if you do, it's just going to cause further behavioral issues and make a very unhappy horse. Unless this horse is extremely trained, not sure if a 10 year old should be on a (what sounds like) green horse. Sorry if I am misinterpreting your situation. How new is she to you and your family??? Can you touch her all over and does she trust you to do so?
So what you'll what to do is keep a rope halter on the horse with a lead line. Start from scratch....Show the horse the bridle...if she flinches or jerks up, you're going to have to get her used to even seeing the thing. Once she is ok with that, you can start by touching her face and neck with the bridle, rubbing it on her and showing her it isn't going to bite. If she doesn't toss her head with that then you can start putting your hand on top between her ears and holding it there, touching her, bending her ears and so forth. You only move on to the next if the horse is not showing any anxiety with the previous step. What I did with my 3 year old, was keep a horse cookie pressed between my hand and the bit and allow him to smell it. Then I would bring my hand on top of his head to help remind him to keep it down. Hold the bit inside your hand with the outside fingers and the cookie laying flat inbetween the bit and your hand. When they go for the cookie, slip it in without hitting the bit against her teeth. It's very important that you don't bang it going in or out. Hope this helps. There are other ways to do it, but this is one of the SHORT STORY versions. I would put more details in, but have to get back to work sorry! __________________