Add a feature to black out or red flag PTO days on the calendar

We are a smaller company (daycare) and need to limit the number of people off per day in order to meet state licensing. It would be wonderful to be able to red flag or black out days that we feel that are at capacity, so our employees know when they are selecting time off days that we are not able to grant easily and will require special permission. Not a feature that will automatically close a day after X number of employees are improved, but rather, one that we can just select the date and say, no-no more easy offs today.