Only offer them one kind of feed at a time. When they run out of starter grower crumbles give them the laying pellets. It might take a day or two but they will begin eating the layer pellets just as soon as they get hungry. It won't matter if your laying birds get starter for another couple weeks or if the younger birds not laying start on laying pellets a couple weeks early.
Mixing the feed so one group gets one kind and the other group gets something different isn't going to work, it's the same way with teaching them to drink from nipples. Chickens naturally go to what they are used to and until that is gone they will continue to go there. When it is no longer available they will begin looking real quick for an alternative and soon find that the laying pellets and nipple drinkers are just fine.
Mixing the feed so one group gets one kind and the other group gets something different isn't going to work, it's the same way with teaching them to drink from nipples. Chickens naturally go to what they are used to and until that is gone they will continue to go there. When it is no longer available they will begin looking real quick for an alternative and soon find that the laying pellets and nipple drinkers are just fine.