Either isolate her....or stop holding petting the other birds.
or you might try.....pecking her back.
I peck them back, on the head or anywhere I can reach, with the tips of thumb and first 2 fingers, as hard and fast as many times as I can before they get away. Well, not hard enough to hurt them, just startle them and let them you mean business. That's what another chicken would do, so they understand that kind of communication.
If that doesn't work after a couple applications, I hold them down to the ground with my hand on their back until they submit....again firmly enough to get the job done but not hurt them....add a few finger pecks and/or tug on the feathers on the back of their neck.