A very sick chicken

[Cayuga momma]

If it is IC they may not die, but they will continue to infect any other birds, present and future, and those birds could die or live and go on to infect other birds. Again that is if it's IC. I wish you could take them to a vet to get tested.
In the end they are your birds so you do whatever is right for you.

 

[MINDANAO DAVE]

About the best you can do is what you're doing. If the one dies make sure you bury her deep so other animals won't dig her up. As to the other's about the only thing to do is watch them closely and if you see them starting to become sick get them on antibiotics. We use erythromycin. Good luck

 

[Eggcessive]

Birds with chronic respiratory diseases usually do not thrive or lay eggs very well. Since they are carriers, they can make other birds around them carriers, even if they do not appear sick. Sick birds may become sick again whenever there is stress from weather or molting.

Rather than buying birds who could be carrying these sorts of diseases, it is best to get baby chicks from a hatchery all at one time for the best chances of healthy chickens.