Pookey does the same thing and that's why I am rehoming her. She gets all stressed out by the other birds perching on her cage even though the other birds don't mean her harm, they just use her cage as a perch. She has gotten better though as most of them have now learned not to do it and she is allowing the senegals to sit there without screaming (she throws a real fit when Davy perches on it and even when he is on the next cage just looking in her direction) but the progress has been way too slow and that's not good for her.
I don't know what to tell you, John. I don't really have a solution for this problem because no matter what one decides, one bird is going to be suffering...