bonding/friendship/aggression

Question
I have three macaws a severe 10 months, a b&g 15 yrs, and a military possibly about 9 yrs. My severe (Boss dna female) ive had since 9 weeks and shes just a doll but my other two I adopted from owners basically. I am the fourth home for Pedro (b&g dna male) whom ive had since march and Roxie (military not dna'd) whom ive had since june no one seemed to know much of her past so im unsure how many homes she has been through.Pedro was first owned by an elderly lady whom I was told loved him deeply but got sick and gave him to some family members who then proceeded to leave him outside in a cage 24/7 when he was interacted with he was smacked around when his behavior wasnt what they wanted and their children poked sticks at him thru his cage bars. The owner I got him from saved him from that only to have him locked in a room locked in his cage constantly with very few toys and only a radio to keep him company. She had her heart in the right place but worked to much and of course he acts aggressively by this point so she was scared of him. He is very aggressive will lunge even just trying to change his foos and water.Roxies last owner loved her but my understanding they switched her from this ladies dad to her brother to herself within a few years and the only one who interacted with her was the father other then when he was around she spent her time locked away and mostly ignored. Shes not really aggressive but shes nippy and cant be trusted as she doesnt give a warning I can see before she just bites the hell out of you even while on you.Thats what I know of their history but now heres the present.I keep them all three in an room of their own its an extra living room area so walk through traffic is common so theyre not really ever just alone, big birds on one side of the room and the smaller one on the other. They are not in cages I have built them an area with braches screwed to the walls and large pvc playgyms connecting into that. So they have lots of places to climb, hide, and plenty to chew on as I replace the branches as needed. I do have a cage that they use for having outdoor time when the weather allows but they are never locked up. (The big guys NeVeR bother the little one and she stays away from them also:) They have many toys to chew and im constantly trying to build new ones lol.The problem: They have decided to buddy up. Both already being aggressive and neglected this has worsened the problem. Neither will take treats from a hand without trying to take your finger in the process, clickers are a huge scary noise that riles them up for an hour upon hearing it, and sticks or dowl rods are a huge no no as a step up perch they will shred them on site. So I just dont know what to do. I dont mind if theyre never cuddly birds like my severe but im so tired of getying lunged at or bitten when im just there to clean or change bowls, showers are a big no unless in the cage outside and then its more forced then fun. This aggression seems to slowly get worse I had one person tell me to seperate them but that was just a terrible mess Roxie didnt seem to mind it but Pedro screamed nonstop and even got down from his area (something he NeVeR does) to search for her calling through the house. What is the best course of sction for these two? Even before Roxie came along Pedro was already this aggressive and while Roxie was in a quarantine after we got her she was friendly'ish. Would come to me to be held and pet on the head only anywhere else got you bitten but now nothing feom either of them. She is now just as bad as he is except over the bowls. She is usually the one that chases him back when I try to fed or water. She nips at him and pushes him the opposite way from me alot of times. She doesnt want to be touched evem when she tries to trick me thinking shes giving me nice signs only to wait till im in reach and then bite me. Im at a loss, I know I got in over my head a bit here but I had the funds to get them and knew I could give them a good place to live, attention, and proper veterinary care which they had not recieved. Any ideas are much appriciated and im sorry this is so long I just wanted to make sure you knew their histories as im sure that has influenced their present. Everyone keeps telling me to separate them but this isnt possible. I only have one cage and the time I tried my Pedro screamed so loud and so nonstop that he literally burst my eardrum. I just dont know what to do anymore. Im tired of being bitten when all im trying to do is feed them. Please help!

Answer
Hi there, thank you for your detailed question. I have experience with various bird species and I have anaylysed your question carefully. The main reason leading to Pedros' agression is his lonley past. I have heard several people saying that they had parrots such as african greys which where fully tamed and after 20 simple days of not attention they completely became "wild" , agressive and biting. The reason to this is that most , if not all, birds are extremly sensative. Sensativity can have various shades. For instance, my cockatiel is really sensative that even if i remove his favorite toy, he gets really annoyed. Pedro,suffered a lonley past in which he lacked attention which led him to transform and develop a negative attitude. As for roxie the main reason that is leading her to become nippy is jealousy. You stated that each time u change the food bowls she gains dominance over the other bird and starts pushing it and that means she is trying to seek your attention and is jealous that you are giving the other parrot (pedro) attention too.

How to solve this?
The best way that i recommend is that to place their cages, toys and everything in a place where people , friends or family members are always there. Not a place of traffic but a place that they will have people talk to them , chat with them and not only one person solely giving them attention. You can adjust your parrot room to a living room/guest room/persons room where people are there from time to time more than 3 times a day. Work on this for a few months and you will find massive change to their attitudes then after  they have become much more stabilised then you can begin handfeeding them and allowing different people to show attention and handfeed them their favorite treats. By time, you parrots will become the loveliest creatures. Another thing i recommend too is to have 2 different food bowls and try your best to socialise, read a story next to them or act gently to them. It may seem hard but definitely possible if you work hard , have patience, diligence and effort.
Like my fb page named bird tameness where i help worldwide bird lovers
subscribe to my youtube channel named "bird tameness"

Regards
Parrot whisperer