Bantam cochins and light brahmas gave me my first chicks. Once they got started they didn't want to quit. They even hatched out chicks in the dead of winter. WHY I had to have a bator I just can't understand. I have a barn full of ma nature bators, and they do a much better job than the man made ones.
Some percautions do need to be taken to ensure the safety of newly hatched chicks. The moms are very protective of their new little charges but things can happen. If ma hen is agreeable, she and her clutch should be moved to a safe place where other hens can't lay new eggs in her nest and possibly break or dirty the original eggs. The hen and her chicks should be protected from other hens and roosters for a few weeks until the little ones can get around pretty good and they understand what ma hen is saying when she makes certain sounds, like "RUN FOR COVER". A special feeding and watering place needs to be set up for the chicks so they can be fed their chick food and have a waterer that they can't drown in and the other chickens won't eat all their food. Chick food is like a treat to hens and roosters. I think everyone should experience little chicks that are hatched and cared for by their mom at least once. Watching them is better than most shows on TV.
Don't give up, it is early in the season and your hens have plenty of time to hatch out another batch of the cutest little fur butts ever.