Broody hen - 1 chick, 3 infertile eggs - supplement with incubated eggs

[Nooby-bator]

First time with a broody hen and she just hatched her first little fluffy.
I made the mistake of not segregating her from the other chooks and other eggs were added to her nest. We also have had something (a chook or something else) eating eggs and I lost one of her eggs to that.
Now she’s separated and her first chick just hatched. She’s still sitting on 3 eggs but i candled them and they are not fertile. I have an incubator with eggs on day 16. Should I swap out some near ready incubated eggs with the infertile eggs beneath her so that i don’t just leave her with one chick (I feel cruel removing her infertile eggs while she’s sitting on them). Or is there every chance that she will hop off the eggs soon and forget about them? I don’t want to ruin my chances of eggs hatching by putting them under her and her abandoning them.

 

[ChickenCanoe]

Let's set the egg eater aside for the moment.
Removing infertile eggs when a hen already has a live chick is less cruel by far than to get involved at this point.
A hen will, in my extensive experience with broody hens, always abandon unhatched eggs when she has a live chick to care for. (a bird in the hand is worth 2 in the bush). I think it is too late to add eggs, even those on day 16. You will likely lose the incubator eggs if you try that because with a live chick, she is unlikely to devote any more time to an unknown future.
I've had several hens hatch and raise a single chick.
There is one other option but it isn't a good one. Take her eggs and chick away from her and put the incubator eggs under her. She may remain on the nest - or not, in which case you lose them too.

A better option, take her infertile eggs away. Let her concentrate on raising the lone chick.
When the other eggs hatch, you can consider the option of trying to get her to adopt them too.

As for egg eating, If the eggs disappear without a trace, it is liikely a snake. Usually mammals (and chickens) will leave shell fragments and even albumen in and around the nest. Perhaps the occasional raccoon or fox will pick up an egg and carry it off.

 

[Abigrayl]

The baby chick will die if it's Mom doesn't focus on it and leave the other eggs. I've had that happen before. Take the infertile eggs away and let her start being a Mom.