Direct reports with multiple managers

We have a 99% external user use case, and we are a training company. Our "Departments" are individual automotive dealerships. We want to give managers at the store access to the manager experience as we feel it gives them a very clear view of what their people are doing throughout the training. However, we have let's say 7 managers at one store that need to oversee the training for all sales staff, as the managers rotate throughout the day/week. We want to let each salesperson be a direct report for each manager, vs only having one manager get access to that salesperson's progress.

We feel that you shouldn't handcuff a user to just one manager, as you might have multiple managers overseeing the status/progress of the same user. Or take it out of our use case. I'm part of a large corporation, and my marketing department consists of 3 managers and 5 junior marketers. I don't have a linear you two report to manager A, you report to B and you report to C. I want all 3 managers to just ensure the training of those 5 users is done, but I can't do that because I can only put each user under one manager. We should be allowed to have multiple managers assigned to a user for visibility.

This would provide an increased adoption and success of the training program as it is the cleanest and 30,000 ft view of training progress the platform has, but we are stuck only allowing one manager to see a specific user vs multiple.