First time letting my broody hens sit on eggs. I didn't want to end up with too many so they each got two eggs. One was not fertile (candled), the other just disappeared. The remaining two looked great when I candled them but today I noticed that each of them has "peck marks" in them or possibly another egg dropped on them since they all like to lay in the same boxes.They are not big cracks, but they are cracks. Nothing from the inside looks to be coming out of it. My question is....they were due to hatch on Thursday Sept 11th. Should I just let them go and see what happens? I have read about bacteria getting in the shells somehow and harming the chick. What do I do?