I have an aviary set up, with a breeding cage inside the aviary. My first pair of budgies are raising the first clutch that I've ever been involved with, and have done an amazing job with their chicks. I've not had to intervene at all, other than just checking on them regularly and cleaning out the nest box. The hen laid 8 eggs, with 6 hatching. The first chick is now 5 weeks old, and has just come out of the nest box a couple of days ago into the breeding cage with the parents. Today, the next 2 eldest chicks have come out of the nest box into the breeding cage. There are now 3 chicks remaining in the nest box, with 2 of them peering out of the nest looking as though they may come out in the coming days. However the youngest one is almost 2 weeks younger than the first chick, and hasn't got all its feathers yet. Still quite a bit of skin showing. The mother is spending most of her time now out of the nest and instead in the cage.
My question is, should I be concerned that she's not being very attentive to the young chicks still in the nest box, especially the youngest one? Ahe was always in the nest box until the first few came out. Also, I'm wondering when I should open the door to the breeding cage to allow the parents their freedom back into the aviary, along with the baby birds that have come out of the nest? If I do this now, will the parents still come back in to look after the youngest chick over the next couple of weeks while it's still in the nest? I also have two other mature birds in the aviary - a placid male, and a female who is very curious about the chicks and wanting to get close to them through the bars of the breeding cage. I wouldn't want the other mature pair that are in the aviary going into the breeding cage and interfering with the remaining chicks, or starting to breed due to having access to the nest box. I also don't want the parent birds to start thinking about having another clutch either!
I did a lot of research on breeding budgies before doing this for the first time, and I was pretty confident with each stage up until this point. When I look it up I'm getting lots of conflicting advice. Would love some real advice from those that have done this before.