She needs to pay for the two days. By asking you when you were closed she was hoping that you were going to be closed the whole week so she didn't have to pay. I assume though for Dec 24 that even though you are open for half the day that you have given the parents the option of taking that day off. It isn't fair to the parents either to be open only half a day if they can't take half a day off and either work or take a full day. So this mom would also be allowed Dec 24 as in you are in effect taking time off that day but opening only for a few hours for those that really need it. But she should pay for Dec 27 just like the others will be. If she isn't paying for Dec 25, or 26 because they weren't her scheduled days then she pays for both of her days in lieu of the privilege of having Dec 24 as an optional day since other families are paying for a minimum of 4 days that including the stats.