Removing/hiding duplicate cells function advanced

Hi all,

  I am trying to make an advanced semi auto staffing sheet/depth chart for work. Say I have 30 positions to staff. I want to be able to list those positions and 3 to 5 people who are capable of each. When I select them in a position I want their name to be removed from other possible positions. For example I have Bob, John and Jane. All three can do job A but only Bob and Jane can do job b. I want to be able to have a staffing sheet where if I enter in Bob for job A then the list for all other jobs will no longer show him. I'm looking for a function or set of functions to be able to do this. Here is a crude example of what the raw data would look like and where I would be entering in a name.