Not sure what formula to use to set up work schedule

I'm trying to redesign the work schedule for a 24 hour police dispatch center. I'm trying to figure out the most efficient way, and I've looked at using vlookup, match and index and still not sure how I should do it. I need to create a list of employees on duty in 2 hour increments throughout the day by looking at the main schedule to see if they are working, then look at the time they are on duty, and then list the employees on duty at that time by seniority. For example, I need to list employees on duty from 1200 pm to 200 pm, but at that time there are 3 overlapping shifts to look at and then I have to put it in seniority order. I don't want my list to have any blank spaces and I cant delete any rows. Finally, I don't want to use macros. I'm attaching a template to you can see what the daily schedule looks like.