I think Petey is getting it.
She's been less aggressive of late with my other birds. Mind you, if they get too close, she'll be wanting to attack, but her idea of what is too close had gotten better.
Lately, I've been rewarding her for not chasing birds if they flew to "her" playgym. She's getting praised and, most importantly (to her eyes I'm sure), she's getting a Nutriberry (only one of the treats I can bribe her with, dried papaya and noodles being also favorites of hers).
She's a bright bird. Didn't take her long to figure out that tolerating the others a bit better means getting treats.
Of course, if the others are out, they also get a treat. Piper, Shade and Zuri need to give me a kiss for it. I'm also working to get Joey to do the same, although he's not catching on as fast. Might be because I think he's the less food motivated bird I have. As I'm writing this, Zuri is eating the discarded half of the Nutriberry he got.