Glad the one was able to be reunited with it's Mom. I don't think they are robins. Our baby bird had orange feathers on it's belly already. We raised a baby Robin a couple years ago until she was old enough to fly away. She was a sweet little thing that bonded to us and I swear that every now and then, she comes back around and talks to us to let us know that she's fine. Sounds like you're doing everything right for now. When they start getting a little older, you'll want to move them to a little cage (a fish tank with a screen on top works good). Find some grubs and worms and let them lose in the bottom of the cage (put dirt on the ground too). Keep feeding them but space the feedings out longer around that time. Once they start hunting the bugs on their own, you know that they're only a couple weeks away from flying the nest. They will be able to fly pretty well before they start catching the bugs on their own.
