I had 3 broodies last year, couldn't stop them so got some eggs from nearby for one of them, and most hatched. The others l gave a variety of eggs from the hens l have and most of them hatched. I have an Indian Game sitting on eggs now and she has 2 weeks to go. Last year she went a bit mental and got so excited when we went to see her she started to trample the chicks. At 3 days old we moved them to another hen who had hatched her chicks and she took them in and reared them. Hope she does better this year. I have never sprayed eggs, leave the hen to sort them out, and move the broody off the nest for exercise once a day if she has not come off herself. I have had eggs that have died before they hatch but l put this down to the age of the hen who laid the eggs, she was not quite a year old and l rushed things a bit. Don't know if that was the cause of the dead in shell chicks but none of the other eggs died. If you have a cockerel and the eggs are not fertile you may be better getting eggs from someone else. Don't know what you can do about the broody, l have found that they get over their loss after about 4 days and you give them time. If she is still sitting and broody you might be able to get some day old chicks and put them under her, but if she does not like them you are stuck with rearing them yourself. I thought of doing this once but didn't want to rear the chicks if not successful. I am not an expert this is just the way l have done this.