When I had one sitting, the one hatched chick was lying away from the hen who was oblivious and focused entirely on the eggs - if doganjo hadn't happened to be visiting and take a look at that time it'd have been dead. I moved the clutch and chick to a more secure location and a second one pipped a couple days later but she kept pushing it out and focusing on the rest - dud eggs and live chick. I didn't have alternatives, had never had a broody before, so just kept putting it back but the poor wee thing died as I didn't know whether to help it or if that would make more problems
With hindsight, since she took the chick on, I would have helped the chick out of the shell and popped it under once standing, but I had a vague recollection I shouldn't and I couldn't remember why..
Good luck with your orphan - mine is now nearly 17 weeks and out with the flock, tho she doesn't roost or eat with them yet she's scratching and resting among them during the day. She'd be 26 weeks on 19 December so I'm wondering if I'll get a first egg laid under the holly bush or behind the ivy on the wall..