You are waaaay ahead of you horse. You need to have your butt more centered. Make sure you have a lot of bend to that knee so shorten those stirrups. You will be more balanced and not looking like you are about to topple onto her neck.
Keep your elbows in. I see in the second picture you have them out.
Keep your hands closed and not flat on the reins like you have in the third picture.
You need to ride with your hands a little bit more up the neck, and not "stand up" in the stirrups so much. You're pinching with you're knees, and your leg is slipping back. Jump without stirrups and through gymnastics to help improve this. Make sure you're stretching through your heels, too. Sit back and wait, when approaching the jump. Let the thrust of your horse's jump close your angles, and don't jump for him(:
Yes,but you do not know how solid of a rider she is. I'm not saying she is a horrible rider. I do not know this but telling someone to ride without stirrups can influence them and then they end up getting hurt. Most people don't ride without stirrups and I am sure she would still be pinching at the knees...I know I would if I had no strirrups. She just needs to learn to ride without pinching and she can do this while riding on the flat first.
Before I got a saddle I rode bareback all the time and Marlea works better for me bareback. She's easier to collect up and doesnt refuse as many times. Because my position is better when I havn't got a saddle.