Formula that subtracts from multiple totals based on date first entered

I have a sheet that that tracts makeup hours I am required to work. As part of the sheet, I have a list of all of the holidays and time off. After each date, I have a limited time to make up the hours and I am required to document what each over time hour applies to. My sheet tracks weekly totals and total hours made up and total make up hours remaining. However, I need a formula that will allow automatically deduct hours from the holidays once those hours have been made up. For instance, I have a week to make up hours missed for Christmas Eve and Christmas Day and then another week for New Years Day. My total states I need to make up 24 hours. As the total of made up hours increases, I want it to first subtract the first 8 hours from Christmas Eve, the second 8 from Christmas day, and so on. What type formula would accomplish this?