Hi,
We have a similar function, where advisors have to take a break off work for Namaz and Fast purpose. Usualy they have to work 8 hours of login which includes 1 hour of break for 5 days a week, I in ramzan I give them 6.30 hours shift for 6 days, with two 20 mins breaks, this leads to a loss of only 5 hours on a weekly basis. If you still cant afford to lose these 5 hours, you can ask the non-Muslim counterparts to do OT for 1 hour each, keeping your requirements up. Expectations with the Muslims in such cases are kept to make them understand that such co-operation will be required of them during Ganpati & Diwali fests. Works for me well