I always wondered how people with a joined flock are able to feed certain chickens that are on different diet from the rest.
It's pretty easy.
Figure out which chickens need the highest protein, and which need the least calcium. (Probably young chicks for both of those.) Then buy an appropriate food for those chickens.
Feed that food to the whole flock, and put out a dish of oyster shell.
A bit of extra protein won't hurt the other chickens, and the laying hens can get their calcium from the oyster shell.