I have only ever used a broody hen but I occasionally buy in fertilised eggs to tuck under them.....very useful when you want fresh stock or a different breed to add to your flock. You will get an average of about 50% males to females so you will get plenty of very noisy cocks for eating.  I have found that you need to remove the broody with her clutch of eggs from the rest of the birds otherwise  two other things are likely to happen. All of your other hens will get the urge to go broody too &/or the broody will steal their eggs & therefore the clutch will be a delayed one (this can be very wasteful as the mother hen will give up on the late ones so they get cold & die in the shell while she is playing with her new hatchlings.  

It is a very good idea to mark all the eggs in the initial hatch so you can tell if any have been added. I have an old rabbit hutch I use as a maternity ward. I leave mother & eggs locked in this but place it near all the other members of the flock......it seems to make for better intergration later when the chicks are ready to join the others.  Chickens are very hot on visual recognition & are very nosy about newcomers. This system has worked for me for 10 years. The mother hen teaches them the rules of the flock & will make your life a lot easier as well as keeping them warm & protecting them against the rest of the flock.

Hattie