Making a Vacation tracker

I am trying to make a tracker for approved vacation. Currently I send out a request to my team they go thru and request their dates and then I give a yes or no type answer. once i approve it then that subtracts the numbers of day from how many days they have for the year vacation. Now i am needing to make sure i have 4 people on vacation per week for all 52 weeks. which would be easy if i required my people to take their vacation in full weeks but i don't want to have to do that. i would like to allow them to have say Thursday and Friday off. Then i would need to track the remaining days of that week so that i can ensure that i have 4 people off per week. I added a year calendar to another sheet and would like that when i click approve that it would also add a count to that day so when it it 4 people off for that day it will turn red. Or at least something that i can check at a quick glance. Also would be able to see at a quick glance home many more people i need to get to that 4 mark. i have attached a sample of what i already have. i did reduce the number of employees on my sample but normally i would have 60 total. Any help on this would be amazing thank you.