I had the same confusion when we first got into chickens!
It's okay for the laying hens to eat the chick feed.
It's NOT okay for the chicks to eat layer feed.
x2 what Pyxis said, just feed chick feed with crushed oyster shells on the side. The layers will eat the oyster shells (for calcium) and the chicks will mostly leave it alone.
Once the chicks have begun laying, you could then switch to layer feed again.
However, if you ever plan to do this again (put chicks in with adults) or you have any roosters that you care about their health, you might consider never using layer feed again. Just keep crushed oyster shells on the side and feed starter, grower or "all flock/flockraiser" feed. If you have chicks in the group, it would be best to feed everyone starter until they are grown, then you could feed grower or flockraiser. Layer feed is very specialized feed...only laying hens (especially only hens currently laying and aren't in a molt, ill, old, etc.) should be eating layer feed. The extra calcium in layer feed is very hard (potentially lethal to chicks) on the kidneys of chicks and roosters.