Zebra finch chick left the nest?

i have a few pairs of zebra finches and 1 pair has 2 chicks, one is in the nest with its head poking out and the parents go in and feed it, the other left the nest yesterday and couldn't fly well so we put it in and it got fed with the other chick. today the same chick left the nest and couldn't fly, so we kept picking it up and finally its learning how to fly, but... we've noticed that that chick hasn't been fed as far as we know, the parents sit with it and chase off any other bird that goes near it, it hasn't called for food either so will the parents feed it, is this normal