So do you keep the chicks separate until they are old enough to eat the Grower,
or maybe use a creep feeder??
Aart, until they are about 4 weeks old the entire flock gets Starter. When the bag runs out after four weeks they all get Grower. Why make it any more complicated than it has to be.
I use a creep feeder when I have very young chicks with a broody hen. That's not to feed them anything special, just so I don't have to adjust the regular feeders so very young chicks can get to them. The adults will concentrate on any feed put out for the chicks even if there is no difference other than it's in a new location. And by two weeks of age the chicks are flying up to the adults' feeders to eat out of that, usually with the broody hen standing guard to keep the other adults away.