Thete is no issue with laying birds eating nonlayer ration, but there is potential harm in the younger birds eating layer feed so the easiest answer is feed everyone non-layer ration (many, myself included, go this route). Simply provide supplemental calcium for the laying birds. If the reverse were true a "creep feeder" that allowed only the smaller birds to get to the feed within would work, but would be ineffective for "protecting" feed in this situation as its the younger birds you want to keep out.