As you write there are a lot of variables. I've tried with parent less chicks in the past. It just hasn't worked. It's hard enough trying to keep chicks with good mothers alive if they've hatched away from their tribes and haven't been integrated yet.Interesting discussion. There are SO many variables with every hen and every hatch that I find it fascinating that so many opinions are so black and white. I honestly think that every situation has to be looked at individually and decisions are based on that very individual group of circumstances. In this case I would have done as the OP and tried to save any remaining hatching chicks. I can't imagine killing viable chicks, the point of hatching them was to have them, generally. I can imagine killing non viable chicks or seriously injured or deformed chicks. I probably wouldn't kill a hen that did this, but I wouldn't let her sit again either unless I was well prepared to intervene if necessary. If it happened a second time I would never let her hatch again. I also understand that philosophically people have different views on what is acceptable in keeping animals in general, so one more variable to every situation.
To @Aboddy2u , best of luck with the rest of them, I hope the majority survive and do well.