I know there are is one of the big boys that offers food in a group setup and the ones that eat are the ones that get set up on their own. However, for you I'd suggest setting them up with hides, water and maybe even some crumpled newspaper. Assuming they aren't losing allot of weight set them up and don't mess with them for a week. Then offer them a feed and leave it in over night.. check them the next morning, those who didn't eat.. LEAVE IT IN THERE.. by that night see who ate those who did are good to go. Those who don't leave them alone for a week and try agin..