What does the selection of a master-bias file in Preferences/Pre-processing actually do?

I no longer stack using dark calibration frames, but I do still use bias frames. I have folders containing captured bias frames for several different ROI% settings to use with lights of the same ROI%. I want to use the Pre-processing script OSC_Preprocessing_WithoutDark, but would like to not have to always copy 50 large files over into the home directory of Siril when doing a stack. I hoped that I could get around this by telling Siril to use a master bias file as default, by selecting that file in the Pre-processing area of Preferences. I retrieved a master bias fit file that was generated in a previous run of the OSC_Preprocessing script and copied it into a new folder D:\Siril\Bias_Masters. I then browsed to and selected that file in the Pre_Processing GUI and checked the box for “Use it as default”. But when I then run the OSC_Preprocessing_WithoutDark script it still goes looking for a folder named biases in the home folder.
What is the best way to achieve having that master bias file that Siril always uses by default so that I don’t have to copy the whole biases folder from my calibration library for every stack?

Thanks,
Matt B.

You need to modify the script to use masters and not all the files.