You had people asking questions on your other thread that went unanswered, so will try one more time
https://www.backyardchickens.com/threads/help-my-chick-is-sick-im-worried-someone-help.1276131/
How old are the chicks?
What are you feeding them?
How are they housed?
PHOTOS will be very helpful - chicks, housing and poop.
You need to be very careful if you are going attempt to syringe fluids into a chick, they can aspirate. Better to drip water beside the beak and allow the chick to take it in.
The one with the crop issue - a photo of it would help. Is this chick pooping? What is it eating? Do you provide a source of grit?
Again, the more information you can provide the better.
I agree- age, what they are eating, and housing/bedding is vital to know. If they are young and on starter crumbles and have plenty of water, they shouldn't need grit. I also agree that you have to be super careful when giving water with an eyedropper not to give it too fast nor stick it down its throat-let the chick take a drop at a time on the side of its beak.