Hi,
The bird is more likely to remain wild if kept outside. She won’t form a bond with you if she doesn’t spend most of her time around you. You should not put her in the same cage as the other conure or both birds will be wild. I’m not sure if you meant that your Sun conure is not in a cage, but if this is the case, it would not be safe to have the other conure around. If the Sun conure lands on the other bird’s cage, he is going to lose some toes. Parrots become tame because they lack another bird as a companion. If two birds form a close bond, they lose interest in being tame. They have no need for a human companion. So you need to avoid ever letting them share a cage. They might interact outside of the cage, but if you give two birds free roam, they will not only bond but will spend their time trying to nest and will get aggressive. As for working with a wild parrot, I’ll give you the links to our behavior and training pages to help you better understand behavior and know how to work with a parrot.
Pet Bird and Parrot Behavior
Teaching Your Bird
Thank you for asking Lafeber,
Brenda