I agree with Margypops. Giving this young lady some special attention and positive reinforcement is important. When she does something right, praise her like nuts. Give her a chance to earn some money or an activity to her liking so that she is more motivated to do as you'd like. This is a powerful tool for parents to help kids learn that they are in charge of their actions and outcomes in a positive manner.
I also would recommend the book "Love and Logic". It is about natural consequences for kids. She may need to make it up to a sibling if she yells at them. The whole family will have to curtail the outing if she acts up. Everyone goes home when it happens after a warning.
It is tough sometimes being the oldest child and the one that has the most expectations of. Try to look at things from her point of view, be empathetic, and guide her through in making good choices.
good luck
It is possible she is feeling left out, possibly the younger siblings get more positive attantion , so she is feeling sad and it manifests itself in acting out, If she is good at school it is telling you the problem lies at home , Focus on her positive side and praise her when you see her doing something right ,its hard being the eldest a child does feel sad if the others get more feedback...how about you play some board games with her, have some one to one time ,take just her shopping with you, to help you .Get Dad involved ball games , outside play and Fun .....