VBA Random selection from dropdowns

I'm working on creating a schedule builder. So far I have individual drop down lists in cells D4:D33 of each possible shift time. I also have counters in cells D81:D84 for how many people are scheduled for a particular shift. What I want is a macro to select random combinations from the drop-down lists while D81 < 4, D82 < 4, D83 < 9, and D84 < 9. Once this is done I want it to do the same for columns E through AH. Any help would be amazing!