Zebra Finch Laid Eggs?

So I have a trio of 3 zebra finches, 1 grey regular female, 1 white female and one half white (underbelly and up halfway on the sides) half grey (top of head, neck, back with regular fawn on sides and orange cheeks) male finch.

The birds have 2 nest boxes/wicker finch nests. They started in one, but migrated to the other where they made their nest taking everything from the other nest out and putting it into the second nest box. Then they laid eggs and hatched them for the first time ever. This is the first time she has laid fertile eggs and mated with male instead of staying paired with the other female. She laid 4 eggs and 1 hatched really fast so I have this big grey fully developed baby you can see in picture and then half the size half fluff/fuzz and skin baby which I can only see because I can't see in the back of the nest. The other baby seems to be doing well. Now the white female who is the only one who lays eggs, cuz the grey female has yet to do so, is super broody and into her eggs decided to lay an egg in the second nest box and it's been there just today. I put soft materials (cotton) underneath the egg after pulling it out and that's how I've always done it, but now she and the male seem to be fixated on sitting and staying in that nest. The grey female seems to be occupied with the other nest and I'm not sure how this will affect the babies they already have if she is gonna make another set of babies when the other babies are still in the nest.