That is what I have been doing with my broody Seramas. I gave the other hens a different nest box to lay in but they only seem interested in laying where the broodies are. Everytime I look under them for extra eggs though, I need to put on a glove and prepare for battle because those momma...
As someone who has had broody hens hatch chicks before, this behavior is normal. During the first few days they are not super broody, and some hens are more protective of their eggs than others. It is best not to disturb her for the first few days, then after that she will probably be more...