Rotational Roster For Groups Of People

I manage an emergency response team which consists of around 50 people, made of 5 different teams and these folks need to take part in emergency exercise to keep their skills up. I'm currently building a training/exercise/ roster database in Excel and would like to add a function that tells me who in each team is due to take part in the next exercise. For info: In the actual workbook, I have names defined on the team members and using vlookup to populate the roster via a drop down list.

To explain the attached example; once the person who is at the top of the list (Name1) has done their exercise, they move to the bottom of the list. Then over time, as the others also take part in execises, Name1 is eventually is back at the top of the list the and it is their turn again (this is quite often known as a Squash Ladder, here in the UK). Is there a way I can vba this process via a button or even better (!) by a drop down list?