Broody Hen Saga - Part Four

This has been the longest week - waiting for the rest of the chicks to hatch, wondering if they will hatch.  After the original five hatched, there were five eggs left - one from the original six, three bantams and one RIR.  I have my doubts about the one from the original six - it's four or five days past 21 days, and six days later than the rest of them.  Like I said before, I don't think the RIR egg is fertile, but I hate giving up on any of them, because you never know.  We had sort of a still birth on Tuesday morning - a chick hatched, but it was dead.  Accounting for everything I just wrote, there seem to be only two more possibly viable eggs left.  I feel like I can give these eggs until the weekend, but that is as long as I think they might be viable.

We had another still birth Thursday, so we're giving up on the eggs.  All in all, we have five chicks and two mothers.  Now that one mother isn't having to sit on eggs, I wonder if there's going to be a problem?  I have other questions too - like, when is it safe to let them mix with the other chickens?  I'll have to reread some of those chicken books I got from the library - especially since I skipped the part about raising chicks at the time.