True enuf that one cannot force a hen into a broody mode. However one can encourage it by using fake eggs in the nest/s. I use golf balls (will kill snakes that eat them), works the same as plastic eggs. I take out an egg and replace it with a golf ball. It may not be the hen I want that takes the nest, but most often one of them will by the time there is about a dozen eggs,, balls in the nest. Then after dark remove the balls and put back the eggs I want her to set on. I also put her and the nest full of eggs in a breading pen so no other hens can continue to use the nest.