This is the last place I'd try to get advise on caring for a living thing. I know home depot and lowes have books on chickens near all the do it yourself books near the registers.
Can you place a flat board right up to the "cubby box"? They could then walk down it to the ground. Also, make sure their pen is secure so nothing gets to the chicks like they did to your other chickens. Get some chick starter right away from your local feed store so they have something nutritional to eat!
I'm a first time chicken owner since my irresponsible cousin left 4 chickens, (3 hens & 1 rooster) at my home since there is a HUGE coop in my back yard which I believe was used for gathering eggs and selling them many many years ago. Anyways I've taken responsibility for them & a week or two ago something killed 2 of the hens and the rooster so only the broody hen & a clutch of 12 eggs are left behind. She's been sitting on them for quite some time & hasn't let anyone try to touch them so we haven't been able to move them to a lower place or an incubator. And now they've started hatching not sure if yesterday or today but my sister spotted two babies under the broody. They're in a coop cubby box (sorry not sure what they're called but they look like cubbys) and it's on the top ( not super high from the ground, probably under my chest I'm 5'5) and I was wondering how to safely move them so they don't injure themselves & so they have access to food and water?? And any other tips for caring for the hatchlings would be greatly appreciated.