If the babies are crying to be fed then it's not their choice to eat less, and if the parents aren't doing their job then you need to do it.

If your mama bird isn't cinnamon then any cinnamon babies have to be girls. Cinnamon is a sex-linked mutation (like pearl and lutino), and the inheritance rules are complicated. The short version of the story is that you can't get a boy with a sex-linked mutation unless the mother is visual for that mutation.

That was a much better way of explaining it.

Thanks.
I saw undigested seed in chick's poop. Is it very bad?
Parents do eat a lot of dry seeds. They do eat something else but I've noticed they crave seeds really bad recently.
I tried to handfeed (the hungriest chick) but ran into a problem of formula too cold (he got some though). I will go on tomorrow. I wasn't very well prepared. Lot's going on.

They say its bad but my Marshmallow had undigested seeds in her poop as a baby but she is living and pooping fine right now.

I mean that recently their poop doesn't look the same, and parents don't eat a lot of soft food like before.

You need to handfeed the chicks. Seed that passes through undigested doesn't necessarily mean that they're sick, but it does mean that they didn't get any nutrients from that particular seed. They're still growing and they need calories but the parents aren't providing what they need. Add a tiny pinch of cayenne pepper to the formula the first time or two in case they have some bad bacteria disrupting their digestion.

I looked at everything closer. Actually parents do feed them, and chicks look not distressed.
What kind of poop should they have at 4 weeks or just before? I just fed one and she passed poop that looked thin (form, not consistency) and dark (no seed in poop). I know light-colored thick poop that they have at the first weeks. Does it change before they start eating on their own?

Again, handfeeding here is complicated Do you normally feed chicks when parents are around or far away? I decided to get one chick at a time for feeding, leaving nestbox and the rest of them at place so that parents could feed chicks who are in the box if they come to feed (and our parents do come often, maybe to just check). I know it sounds weird but normally I remove the whole box from the cage for measuring them and cleaning. our box isn't mounted, its standing on the cage floor. But all big birds are making such a big deal out of it, if they see I do something with one chick on the table. I mean they don't attack or anything, but they watch me with caution. When the chick sees or hears the parents, she stops eating from me. Last time I was taking chicks downstairs to feed but its pretty cold there so I will try to avoid it.
I fed two today. That's it for now. I don't measure milliliters, its impossible, most is spelt on the table. Another reason is that I want parents to go and feed them before night, instead of being alarmed of me messing up with the chick.
Of course, its much easier to feed them when they are not flying yet.
If I have some formula in the cup, that is cooled down under 100F (say, after feeding of one chick), is it OK to add new formula to it plus hot water and make more amount? I made formula twice today for two chicks in two different cups. But if I do it for 5 chicks.... its going to be crazy.
How do people feed more efficiently? Make a big cup for all of them or several small cups? Have them lined up or take them separately? Have parents close by or far away?

About the hen. I can see her sitting sadly with her tail up sometimes, but she is not bothering the cock too much. hope it will stay this way

I reheat the formula by heating a bowl of water in the microwave, then putting the cup of formula in the water and stirring it with the thermometer while it absorbs heat from the water. The actual formula should not be microwaved, you'll get dangerous hot spots that way. The cup of formula will stay warm longer if you leave it sitting in the bowl of water while you feed a chick.

The chicks' poop will vary depending on what they've been eating.