Birds will eat as mom & dad bring food but it takes them some time to find that food. You are there with plenty of food and the birds get full quickly. If they don't open the beak for you they are not hungry so let them sleep. I would try to give them a full crop at evening so they have food for the long nights.

I found my dog and she killed the mama bird there is no rehab center or stuff like that but I need Toni I have 4 baby birds I live in the country 1 egg not hatched yet they are 2 days old HELP