I have a second clutch of eggs under a setting silkie hen. The first hatch (actually, 4 hens who laid and set simultaneously, 3 sharing the same nest area) went smoothly with nearly all eggs hatched normally and chicks running around everywhere. However, the last hen - who wasn't setting with the first group - is now setting a clutch while the others are away raising their chicks. In the past 2 days, 4 chicks have pipped and attempted to hatch out of that clutch, but while the shells cracked and broke away, the membrane inside seems to be dry and tough, and all 4 have died during the hatch process. I assume I need to look into nutrition for the cause. Any suggestions? The flock is on Blue Seal layer crumbles and also free-range around the hen house and yard. They have grit and oyster shell supplement available, as well as access to the natural grit in the ground. What can I do to ensure better results on future hatches?