It is not the size of the cage but how your bird will react. Each Grey is an individual and may like or dislike what ever bird you bring in. I would have any new bird examined and quarantined before putting them in the same room. Do not immediately put them side by side allow them the distance to get to hear and view each other from a distance first. Pookie is a CAG and at the moment I also have a TAG and another CAG in the house, she ignores them totally. We also have one U2 and an Elanora 2 she will share a cage top with the Eleanora nicely. Hates the U2 who is aggressive so is not allowed out of cage when any of the others are out (he is fascinated with her). One of the other CAG's loves attention but hates other birds Grey or not (jealousy issues) the TAG is not flighted and allows no other birds on his cage(puts his head down and charges) but does love to watch the others during their daily activities and they are all learning each others vocabularies. Unique individuals each one. You know your bird and hope that the room in your cage can be filled if Yoshi has room in her heart and her life. They may work out to be each others best friend and you could be the outsider as well, you just don't know ahead of time.