What started as a whim has become an obsession

I stopped by the feed store down the street one Saturday. I don't really remember why. I ended up bringing home 3 of the most perfect little ladies! Ophelia (a red cross), Mathilda (a leghorn), and Gertrude (a sex legs). Unfortunately, after almost a week, I came home from work to find Gertrude dead in the bin. We stayed at two about a few weeks until, again, on a whim, I stopped by a different feed store. I picked up 2 silver lace wings (I think that's what they are called). Surprisingly, the four bonded very well. I had no issues introducing the ladies. Last Sunday I cleaned the coop, but I completely forgot to shut the top of the nesting box. My heart sank when I went to check the girls and realized there were only 3 hens left.
I decided to give it one more try. Today I bought two very young brama chicks. One seems pretty strong, but the other is so small. She started getting weak and didn't seem to be thriving. I looked for help here and saw something about cleaning her little bottom with a wet cotton ball. She has perked up a bit, but I don't think she is eating or drinking much yet. I don't want to loose another life. I'm hoping to find help here.

 

An update on the weak Brama - she didn't make it through the night. I think she was just too young. So now I'm left with one chicken in the tub alone. I have 3 others in the backyard, but this one is too young to introduce to that group yet. I know (or maybe think) that chickens are not loner beings, so I wonder if I need to go get her a nest buddy right away or can I raise her by herself for the next month until she is ready to join the other flock?