What is the analysis of that feed, it should be on the label? What is the percent protein and what is the percent calcium? The marketing name "Finisher" doesn't tell me much. Broiler Finisher might be different than Layer or Game Bird Finisher. What are you working with?
My guess is that the calcium is right at or below 1% since it is a Finisher, not a Layer. That amount of calcium won't hurt the chicks. Do the broody hen and her chicks also free range? If they do and forage for a lot of their food then the percent protein or calcium is less critical. If this Finisher is all they eat then it becomes more important, both amount of calcium and protein. If it is most of what they eat then you would want a reasonably high protein feed for newly hatched chicks. The broody will benefit too.
For the laying hens that free range a lot it's probably OK but I'd still be interested in the percent protein. I'd also offer a calcium supplement like oyster shell on the side. They may be getting enough calcium from their environment for the egg shells, especially if your native rock is limestone, but if the egg shells are thin a calcium supplement is a good idea. The thickness of your egg shells will tell you if they are getting enough calcium.
Since yours free range and forage for a lot of their own food you don't have a lot of control over what they eat anyway. It's not like a small backyard flock where you control all they eat. For thousands of years chickens have managed that themselves on small farms worldwide, often without supplemental feeding except in winter. Some of that depends on the quality of forage they have. There is a big difference in them foraging in a neatly mowed back yard of only grass that is not allowed to go to seed versus a farm with various livestock and areas that are not mowed so they can get a wide variety of forage. Creepy crawlies may be easier to catch too. It's' not what is in one bite, it is how much overall calcium, protein, and other nutrients they eat in a day, and even that is averaged over several days.
I don't know your goals, for some what they eat is more important than others. For example, if you are raising then for show you need to manage their diet fairly tightly. I don't know the quality of your forage. There is a lot I don't know about your unique situation. My gut feel is that you will be fine with that feed, but that's based on some assumptions I'm kind of reading between the lines of your post.
