Parrots will be parrots, first. It's unreasonable to expect them not to bite, or attempt to bite. It is a form of communication. Snickers communicated with extreme prejudice, but for a very good parrot reason.
Diffusing and essential oils have entered the companion animal arena with great success for some, and a sad end for others. The thing about diffusing essential oils is; it isn't essential. But it does require essential understanding.
Your book is amazing! If only I had found it while my poor parakeet was still alive. I still feel guilty daily for the life Sky lived. I got him when I was eight and completely irresponsible and clueless about how to take care of a bird. In the first few months after I bought him, I terrified the poor guy out of his mind, trying to play with him like I would a dog, treating him like a toy. He was fed an all-seed diet, and a few years later, when I was better educated, Sky was already convinced humanity was evil and anything other than seeds was poison. He died young, at only five. If only I had known about your methods, I could have helped him sooner. I am determined to not let any of my future birds suffer the same fate as Sky, and also want to adopt. I can't at this point in my life, as I have two predatory dogs, two rambunctious sisters, and two parents that hate noise and mess. Sigh.