Depending on where she’s sitting, I usually just slide a hand flat under the broody, lift her straight up, look under her, and set her back down once I’m satisfied she’s only got the eggs she should have.
If you move her you’ll want to make sure she can’t access any other nests, or watch her when she gets up to make sure she goes back to the right nest. I would just pick her up from her current nest and move her and the eggs to the new one. It may help to do so at night. If you put her in a cage...
First, mark the eggs you’re letting her sit on and check under her every few days to take any eggs other hens could be laying in her nest. I like to have a separate area ready where the hen and chicks can be closed off from the rest of the flock, but I don’t move my hens in there until just a...