When the eggs hatch (around 27 days), make sure you provide the parents with an over abundance of soft foods ( at 8/9am, 3pm, and 9pm). An hour before the lights go out, another bowl of food that won't spoil by morning should be offered such as sweet corn, sprouts, fresh fruits, and veggies. Sprinkle all the soft foods with Wheatgrass and provide unlimited Pellets. The birds will gorge themselves shortly before lights out and feed the babies during the night. They will finish off the rest of the food in the morning.
I have never raised baby birds but I am taking the infos from the book : "For The Love Of Greys" by Bobbi Brinker.

That should help you until Danyall gives you more infos as he has raised baby greys before.
PS: I think the babies stay with the parents for 2 or 3 weeks.