I ended up taking the other chick away last night. I felt bad for the hen, but I just didn't feel confident in her mothering skills. I had moved them to their own pen within the chicken run. Again the mama seemed protective, but she kept burying the water with leaf litter. I tried replacing it many times. Then I bought a water bottle for bunnies, but the mama wouldn't stun mmm from it. I gave up, and brought the chick in.
The lost chick was my son's, so I let him pick out a replacement to keep this one company. But, now I am worried about it. I will see if I can load a picture. It has a sore on its leg and looks like they removed it from the egg before it was ready. I bought it from a local breeder. Sigh. I need a break.