These horses need to be dealt with separately.
The paint needs to learn how to behave when you walk into the pasture, so she needs exercises that teach her that when you are in the paddock, YOU are her leader, and you need to take control of that situation; when she charges you, don't back off. Have a lead rope, or whip, so that you can ask her to back off. When she points her rear to you, make her MOVE away like, yesterday!!! Do not tolerate any horse pointing those two barrels at you, ever! If you have too, pen her separately for a while so you can work on this behavior without interference from the other two horses.
With your riding horse, when she is acting barn sour under saddle, or even on the ground with you, make her work hard near the paddock where she wants to be; then take her away, and let her rest for a bit AWAY from the paddock/her buddy. When she gets unsettled or unfocused, take her back to the pen and work her tail off some more; The idea being here, that if she wants to be at the paddock when you're working with her, then you are going to make it uncomfortable for her to be there. Get her attention back, and keep it. She get's rest, affection, and attention away from the paddock and her 'buddy'. With your bay mare, you really need to make her feel like you are a leader that can be trusted again, not just for attention, but for correction, since she has obviously decided that the paint mare is more important at the moment.
"The ideal horseman has the courage of a lion, the patience of a saint, and the hands of a woman..."