Welcome!
Merlin, our

, likes his food in his bowl - he generally will take treats from your hand, open his beaks, and lets them all fall out - brat! That's just the way he is.
Unfortunately we don't have birds who have been breeder birds, so I can't offer you a lot of advice.
Merlin only growled at me the first few days I had him as a baby - he was not sure of his environment at all, and had been driven 500km to me by his breeder's mate with crazy long painted fingernails. It's a grey sign of uncertainness.
Take your time, and he'll let you know how comfortable he is with the situation. You will learn a lot about his feather fluffs, eyes pinning, and body movements as to what he's ready or in the mood for

Good luck, and I'm sure someone who has dealt with breeder birds will be able to assist you further!