I got there and Mama Cat immediately took me to her baby. She then kept trying to give me her baby and when I kept putting it back in the safe, warm cardboard box, she'd go put it somewhere unsafe and cold. She obviously wasn't moving it to a different nest. She was obviously starting to reject the thing. The lil baby got hungry at one point and started screaming and mama cat put it in the middle of the parking lot and went and laid down on a chair. I put the baby with her and it got to eat and Mama Cat moved it to the box again eventually. I'm hoping she doesn't abandon it. If she does, I'm going to offer to raise it. I've bottle fed and raised dozens of kittens, so I know what I'm doing in that regard.
Can you bring her inside with the baby in a small room? It seems like less work than hand feeding a kitten. I'm wondering if something is bothering Mom about the barn situation.