No probs for the hijack. It's related. Broodies are seen as a problem and can be if you don't want them to be but the old boys always said 'never waste a broody'. So I'm thinking that now I have more flat land I need to set up some kind of nursery pen. Needs to be 100% rat proof and I'm wondering whether to have a bigger pen with lots of small houses and just put them in when they want to sit and let them get on with it, or create a few smaller pens which could be rested between hatches.
No doubt letting a broody raise chicks is easier in many ways. You don't have to keep them warm, clean them out (usually) or anything else. As long as there is fresh water and food, mum will raise them to 5 weeks or more no problem.
As for the question on opening the failed eggs, I did in a few batches and they were very wet which is really why I concluded that too much humidity was the issue. I must look into egg sac sizes. Problem with copper marans eggs is that you can't see a lot!