It depends on the size of your hens. I used to put a dozen guinea eggs under my Brahma/Cornish hen. If all 12 were fertile, she would hatch all 12 on day 26.Okay, then I guess I'm back to the broody hens no matter what. I don't know how many eggs a hen can handle but I will have to split them up between my most enthused wanna-be moms (unless hens can handle 6 apiece). Maybe if I send them out with the hens when the moms think it is safe to do so, the guineas might eventually incorporate the keets into their very tiny group.