Pete isn’t going to respond, because he hasn’t been on BYC in almost 10 years. But did your last two eggs end up hatching?
Usually it’s just a matter of patience. Sometimes whatever causes them to be delayed, also causes them to not be viable. But in your case, they were set later, so they just needed more time.
As for putting some of the hatched siblings back into the incubator, I feel that that would cause more harm than benefit. Getting kicked around and pooped on could tip the scale the wrong way. But, many many eggs get kicked around and pooped on and hatch just fine, so who knows?
It would be interesting to know what you did and what the outcome was.