If the eggs have just been in with the hens, and the hens aren't broody, there will be no development. Do you have a rooster? The eggs will not be fertile if you don't. Also, what do you mean by bought 'bought' broody hens? did you buy hens that were broody when you got them, or a typically broody breed such as cochins, silkies, Old english bantams etc.
If I want my Old English Game Bantams to go broody I'll just leave them to lay in the nest boxes. They eventually find that they have enough eggs and begin to sit. Then I'll take a couple of the eggs (before they begin to develop) and put them in a new spot(a dark nest box area) then they'll lay in there, and hopefully I'll have another go broody. This has worked for two of my girls, but OEGBs are a very broody breed, so it's not always going to work for every chicken.
All the best
If I want my Old English Game Bantams to go broody I'll just leave them to lay in the nest boxes. They eventually find that they have enough eggs and begin to sit. Then I'll take a couple of the eggs (before they begin to develop) and put them in a new spot(a dark nest box area) then they'll lay in there, and hopefully I'll have another go broody. This has worked for two of my girls, but OEGBs are a very broody breed, so it's not always going to work for every chicken.
All the best
