Nearest Enemy To Team (Without Crowding!)

Hi all, I have a script to assign the nearest enemy to each of my 3 team players. However I do not want team members to crowd to the same enemies. They should distribute themselves evenly otherwise they will get picked off as they all focus on one enemy. I can run the find nearest script multiple times and each asking the team players to ignore an enemy character that is closer to another team-mate. However this seems like a very heavy process to run each frame. Any suggestions, is there a better way to do this? T