I'll talk to the neighbors if I ever catch them outside. We are not close obviously. The chickens don't go home to a coop at the end of the day; they roost in the trees on the edge of my property. It would be nice if they went somewhere safer; not as many worries about predation.
Welcome to BYC. If you feel comfortable speaking to your neighbors fine, if not, don't. You said they roost in trees and roam the neighborhood, they sound homeless to me, so if you want to keep feeding them, do so. (A grower feed would work for them, since there are young ones in the flock.)
I'm sure the chickens appreciate your efforts. I know that I do, I always appreciate someone with a kind heart.