Broody duck eggs hatched, but incubated not yet

[The5spades]

Our Rouen duck hen layed 13 eggs, and we put half in an incubator, as we weren't sure about her mothering instincts, since she didnt seem to be spending much time on her nest.
(We candled all the eggs and only found 1 unfertilized). We also don't know exactly how long she had been sitting on the eggs because we had someone caring for our animals while we were out of town.
In the last 24 hours, her nested eggs have hatched, but the incubated eggs haven't yet. All of the eggs are moving and peeping, and one has pipped, about 24 hours ago.
I'm concerned about why they haven't hatched yet. I would really appreciate advice from anyone who has experienced this!
I've thought about putting the incubated eggs in her nest, but don't know how she would be able to care for her hatchlings AND sit on the unhatched eggs.
I'm also wondering about introducing the incubated hatchlings to her, if/when they hatch.

 

[DemeterAD9]

Sounds like it is just a difference in temp and/or humidity. Not a huge problem IMO, a day or two difference shouldn't cause any harm in the incubated eggs. As for introducing the chicks, once they are all dry tuck them in under her at night time. I doubt she will reject them if she's already being a good mother to their siblings.

 

[The5spades]

Sounds like it is just a difference in temp and/or humidity. Not a huge problem IMO, a day or two difference shouldn't cause any harm in the incubated eggs. As for introducing the chicks, once they are all dry tuck them in under her at night time. I doubt she will reject them if she's already being a good mother to their siblings.

@DemeterAD9, Thank you for your reply! One of the incubator chicks literally just hatched about 10 minutes ago, so hopefully that's a good sign! Your suggestion to place the dried chicks under her at night makes a lot of sense! Do you think I should do all of them at the same time, so they don't get lonely in the incubator, or sneak them in 1 at a time?

 

[DemeterAD9]

I would just do them all at once or if they are taking a while to hatch, do the first few and then all the others. It shouldn't take too long, once the first one hatches the others should be out in no time.