You need to provide a solution to provide the sales managers with the required access.

Create a security role that has a table filter on the Sales_Manager table whereusername = UserName()

Create a security role that has a table filter on the Region_Manager table wheresales_manager_id = UserPrincipalName().

Create a security role that has a table filter on the Sales_Manager table wherename = UserName().

Create a security role that has a table filter on the Sales_Manager table whereusername = sales_manager_id.