I was told that I could leave Scout out with the rest of the flock and just change them all to un-medicated starter/grower as long as the older girls had plenty of access to oyster shells and other forms of calcium. That's what I've done, and it's worked out beautifully for us. This is a good time of year to do that because for the most part laying has slowed down anyway. I don't have to worry about Scout getting calcium he doesn't need and the girls get plenty of greens, leftovers, oyster shells, scratch and starter/grower. I haven't noticed any laying issues with them and it's been almost 2 months. The girls that have decided to lay despite the shorter days are giving me good quality, hard shelled eggs. One other note - Scout has a small dish of chick grit. I figured there was no way to keep him away from everything the girls get, so rather than risk crop issues in addition to all of his other problems I'd just make sure that if he joined them in the scratch feeding frenzy he'd at least be able to digest what he's getting. Yours are a little young for that yet, I think, but something to keep in mind. Good luck with them!
Oh, and where in the heck do you still find chicks in a feed store? Inquiring minds........