Best Practices for Replicating Row Level Security Access

Hi,

I have a sales report that has a sales manager slicer that contains each sales manager across the organization. I've set up Row Level Security such that lower level managers can only see data for themselves, in other words they are only able to select themselves in the Sales Manager slicer. I've done this by setting a filter for the sales manager to equal the userprincipalname(). 

My issue now is that there has been a request for additional employees (non-salespeople) to "replicate" certain sales managers permissions.

For example, John Doe is the sales manager of Team A and can only see Team A data. Separately, Tim Smith is the head engineer of Team A, and would like to replicate John Doe's permissions on the report. Without adding Tim into the database as a dummy sales manager of Team A, is there a good way to replicate John Doe's access?

Thank you.