master list into sub lists

[gtrenderer]

I am working on a team list. I have the manager names and all of my agent names. My problem is that the rosters can change anywhere from a monthly basis to a weekly basis. This makes calculations on my reporting much more difficult. Is there a formula to maybe put all the managers names in row 1 and then list the agents under that manager all pulling from a master list from a report that is much easier for me to create. I believe an array formula can do it but im not familiar enough with them to use them. How can I update my list by just dumping a new master list into the document??