After spending the night in the house on a heating pad, I put the new chick under the hen last night.
Today it seems fine, just not sure how to get down the ramp, so I helped it and mother hen was not too happy about that. Since its a few days behind its siblings, it will need to learn/exercise a lot to build up strength.
There is yet another chick trying to break out of the shell this am, we'll see if it can make it. If it can, I'll bring it inside and put it on a warming pad until its stable enough to go outside.