Likely regurgitation (feeding behavior) than 'throwing-up. Connected to introduction, parenting, mating behavior. Much better than attacking the baby.
Vomiting is usually more violent sbd rgey shake their head side to side. And its liquid instead of thick ( usually)
Regurgitation they pump their neck or bob, bring it up in their mouth and try to feed it to something. Usually thick and white like oatmeal. Babies or young bird may not be as controlled...
So its hard to say from your description .
Congratulations on your sun. How many birds do you have now?