Your question isn't silly at all. We all started out at one time or another, and we've all had to ask questions, read books, do research and learn by trial and error. And I don't think there is a single person out there who isn't still learning something. Now that I have all the details, my answer is totally different. Since she does have one left, and it's that old, I would not try to give her any more. I agree with Happyhens that the one remaining chick could bully the others, the others wouldn't accept the hen as their mother, and you're better off just leaving her with her one chick. She'll forget about the others in a few days. She's still clucking because she's still looking for them, but she'll get over it soon.