The bantams are smaller than the meat bird, and probably fly better too. So you can probably set up something where they can reach the food, but the meat bird cannot.
You might be able to make a pen with bantam-sized openings and put the food inside it. Just be sure the food is far enough from the openings that the meat bird cannot reach her head in and eat anyway!
Or you might be able to put the food up on something (like a table), where the bantams can easily fly up but the meat bird cannot.
Or you might be able to make a feeder where the bantams can put their heads in to eat and the meat bird cannot, but it's probably harder to get the right size holes for that. There is usually more difference in body size than in head size.
(Of course the meat bird still needs SOME food, so you'll need to give her the right amount once or twice a day, if you have a feeder for the bantams that she cannot access.)