My heart breaks for you and your loss of Harlow. It is not easy losing a little birdie but to have lost Rocky recently must be tearing you up.
I would have thought you would have had the necropsy done to determine for sure if it is Psittacosis or PDD you are dealing with in your flock. Please, if another bird is ill and dies, please, please, please get a necropsy done. I can imagine how emotionally draining it would be to do but it is so very important that one be done. It is necessary for your sake if it is Psittacosis as that can be transmitted to humans and to determine how best to handle the rest of the flock.
Also, please remember for everyone else's birds health and safety, you should never be visiting any pet stores, bird meeting, bird fairs and such as you are risking contaminating items, people or other birds as you are more than likely carrying which ever disease both these birds died from and I know you would not want to be responsible for transmitting anything to another bird.
I think im still in shock [its been a week]. Harlow was my first big bird and showed me how wonderful Macaws are.The first year of her life she became ill [they thought she had chlamydia]. We were able to get her better for another couple years . This past July one day she started throwing up. Since I lost my Blue and gold Rocky a couple months ago [I was like OMG am I doing this?]. Found out it was unrelated. She was at cornell getting stable then I took her home. They thought her original illness never fully went away and had a flare up.At home I kept in close contact with her doctors [they would send me medicine]. She seemed to not respond to anything and was getting weaker. One day I knew we would have to get her back there. It was almost like she was waiting for me. I pic ked her up and it was like she lost her motor skills . We raced her there ,what she had spread to her brain [and she died]. I did everything !!!! to try and save my beautiful girl 
