Best way to add an item to a Drop Down List Based on criteria

OK, I am using a popup Modal to add, edit and delete records from my DB. I use the same Modal and have it open empty to add a record or filled when editing. I would like to add "Select Employee" to my DDL when adding a new record, but not when editing one. The code below works, accept if you edit first (removing select employee) and then go to add a record it's obviously gone. Adding the "Select Employee" in addDepartment (instead of when the page loads) worked also, but I would get duplicates then adding records multiple times. I also need to make sure the user can't save the record with out making a selection. Thanks in advance for any help.
This is a very simple part of a form containing a textbox for a department name and a DDL that allows you to pick an employee from a different table in the DB.

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.L ...