I have a mitred conure that due to a beak injury has to have his beak trimmed to keep it in shape... otherwise, the bottom part will overgrow, and if it overgrows and curls, it too will end up going up to his nares. I saw, in person, an african grey who had the same type of injury (missing half of lower beak), and since the beak wasn't kept in shape, the lower beak grew upwards and curved.... to say the least I was disgusted! I know of someone who owns a blue throated macaw (if I recall correctly) who also has this same problem. She too receives beak trims and does just fine!
If the vet can work on the beak then I wouldn't worry about it! However, you need to get the birds checked for mites, and also get blood panels done, as they probably have HORRIBLE livers which may be causing the overgrown beak...
Try and keep them on mostly a similar diet, and change it slowly over time. If you change the diet too quickly it could be a shock on their system.
Would love to see pictures of the two!












