I think you have several options, though they are more limited now that they are pipping and hatching. Of course you could keep them in the incubator and brood them yourself, but that is not what you are after. I would not be either.
I would not put the chicks under her in the daytime. She is more likely to accept them if you sneak them under her at night. So I suggest waiting.
One risk if you open the incubator is that you might shrink wrap the chicks. I've done that in a situation close to what you are facing. I did not shrink wrap all of them, not even all the ones that had pipped, but one was shrink wrapped. I don't consider it a huge risk but it does happen. If you do open the incubator before they all hatch, keep it open as little as possible and maybe put in some warm water, not hot enough to spike the temperature since incubators don't get rid of excess heat very well but a little warmer than incubating temperatures to help the humidity recover faster. Sorry but I can't be much more specific than that. It depends on your incubator type too.
I think if you try carrying eggs that are pipping to her nest, you take a much larger chance of shrink wrapping them. I personally would not move the eggs to her at this point.
I don't know when your hatch will be over. I've had them finished in around 18 hours and some take two days. That uncertainty adds to the problem.
What I would probably do is wait until the hatch is over, then slip the chicks under her after she has well settled in at night but before I went to bed. Use as little light and commotion as you can. Then I'd check the next morning when she first woke up. You'll most likely find a very happy hen, but they are living animals and anything can happen. Some broodies kill the chicks they hatch. Not many, but it does happen. She may take another day before she brings them off the nest. It's a nervous time but will probably work out. Those chicks can easily go three days or even longer without food or water after they hatch so you are not in a huge hurry.
Last year, I had a Black Austrolorp raise 15 chicks, all incubator hatched, so as long as she is the same size as a Maran, she should be able to handle them even if all hatch.
Good luck!