I would like to suggest the following two provisions which are widely applicable:
(A) Declare a list of festival holidays before or at the beginning of a year (may be financial year or calendar year). Only shift workers are required to work on festival holiday. You may compensate them by paying one additional wage for that day. For example, if Xmas is holiday During December 2019, then an employee who will work on that day will get salary for 32 day instead of 31 day.
(B) Or, arrange to assign a Compensatory Holiday against the working on Xmas for that particular employees. However, you have to declare first the rule to enjoy that off day. For example, within three weeks presiding to that particular festival holiday.