Notify managers about due courses of its employees

We would like to inform managers (supervisors) about due courses of their direct reports.

We are using due date field for mandatory courses. To increase completion rates and managers awareness I suggest to have another field, either on a course level, or reporting panel to message a respective manager when the course of it's employee is already due. To get such information, a lot of manual work is required because we don't want to spam all managers in organization (more than 1400 managers) but only those who should follow up with their respective team members lack of course completion in a deadline.