Need to get data from one table into another with no connectivity

I have a vacation App.  I have 3 tables: Employees, Managers, Vacation Requests.  Everyone in the company is listed in the employee table.  All of the managers are listed in the manager's table.  Each manager has several employees, but never themselves as you can't be your own manager.  Right now I am using the brand new Text summary field to combine all of a manager's employees into one text field.  I then pass that field back to the employees.  This is basically a list of their co-workers who all share the same manager.

Then when the employee creates a new Vacation request, I create a snapshot of that text field in the new vacation request.  This allows all of the co-workers to see each other's vacation schedule.  If their name is contained in that list, they can see it without having to be able to see that employee's employee record as it may contain private information.

Now I have been asked to allow employees to see the vacation schedules of their manager.  This is proving to be way more difficult than I thought it would.  What I need to do is get a list of a manager's employees in his employee record, so that when he creates a new vacation request he can pass a snapshot of his employees (as well as his co-workers) to that request so everyone on the list can see it.  But that list is in the manager table and since you can't be your own manager, the two records aren't linked.

The two records to have the same user and the same name, but I can't find a way to use that similarity to merge the two.  The Merge field can't be a user or a formula field.  If it were just a one time update, I could do it manually, but as people get hired, promoted, or change managers, the lists will need to be updated.