It's heartening to read that it's not 'over' till day 25. I had the two that didn't make it on day 21, then nothing. Surely they would all want to hatch at the same time? As I'm suspecting my Plymouth Rock trod on them. I'm also thinking if there are any more that hatch I might put them in a box with an angle poise lamp to keep them warm for a few days, or at least until they dry out and are able to walk around. I've raised day-old chicks with the lamp before. Here's hoping the surrogate would accept them back.
Anyhow, I'm not holding out much hope for any live hatch at this stage, but will leave her sitting on the eggs until day 25. *please hatch*