Call my a hypocrite, as I don't recommend allowing different sized birds to interact!
Not to say that it can't be done, as it occurs every single day out in the wild! But, unlike their wild cousins, many captive parrots do not know how to safely interact within a flock setting. Instead of breeding in mixed aviaries or flock situations that may be similar to their wild counterparts, parrots are bred in pairs, their chicks removed from the nest at a certain age, then raised by humans. Even if raised with clutch mates or birds from different clutches of other species, they don't really get to see and learn from adult birds in an adult flock. This can potentially lead to aggression, which could lead to injury, maiming, or worse.
Currently, I have Sylphie, an african ringneck, living with my cockatiels without any issues. The cockatiels have learned to avoid her when she wants something, and the most she'll do is scream and growl at them! I think Jayde could potentially live in harmony with the flock, but Charlie I have my doubts! Charlie is already missing half of his lower beak, thinking he could boss around a blind ruby macaw and he had no tolerance for a little blue budgie that had squeezed herself into his cage while he was inside it! I know that Charlie *can* get along with other birds, as he had a lilac crown amazon as a buddy, and he bossed around two other zons as well without any issues, however, here, he is the largest bird (rather than being mid sized). He and Jayde only barely get along! It's like Charlie wants to be friends, but he doesn't know how to play "nice", and Jayde is sensitive. I'd love it if the two of them got along well enough to be buddies, but I'm also perfectly ok if they remain as "friends at a distance."
I think the main question is, would you be able to handle the blame and the guilt if something *WERE* to happen? I can pull up pictures of a cockatoo and a conure snuggling, or a macaw and a conure snuggling, or a parrotlet sitting on top of a hyacinth macaws head, or a lovebird laying on it's back on the tail feathers of a cockatoo also laying on it's back, of a lovebird feeding an amazon, and a quaker and hyacinth macaw that are buddies. I can also say from experience that the guilt and hatred towards oneself for "allowing" an accident to occur is no fun.
(bird had escaped from her cage while I was out and lost her upper beak, which resulted in the loss of her life
)
Although I know my birds and my flock, and am willing to change things if necessary, I don't know your birds, and that's an awfully big beak difference there!