Your broody is acting just like a broody. She will come off the nest once a day or so to eat and drink. Broodies like to think they're being sneaky when they come off the nest to take care of their daily business, so she's not likely to do so while you're watching her. You don't want to feed and water her on the nest or she may poop in there and soil the eggs. If that happens, they're not likely to hatch.
You could put the eggs in the incubator with the others, but then you will be dealing with a staggered hatch. Possible, but not real easy with just one incubator. If you had something you could use for a hatcher, it would be easier.