Substitution on Holiday

Dear gurus..

I have a holiday on March 1st for 1 particular unit...defined in holiday calendar..

On march 1: daily work schedule assigned is working shift in pws with I march as holiday in Holiday calendar..so day type is 1(off/paid) on march 1st

But some of my employees want working on March 1st.Please suggest how is this possible..?

Regards

Ashima