Add item to Combobox if no match found

[sharky12345]

I have a Combobox which is loaded with current staff names by this;

lRow = Sheets("Setup").Range("A" & Rows.Count).End(xlUp).Row
ComboLink1.List = Worksheets("Setup").Range("$A$2:$A$" & lRow).Value

The box is then populated by the click of a Listbox item;

ComboLink1.Value = ListBox1.Column(2)

However, the Listbox is retrieving data from a large spreadsheet which may include details of retired staff, so is there a way I can get it to add 'Inactive Staff' to the Combobox items if the value from the Listbox isn't found? The Combobox is available for other functions so I don't want to simply add 'Inactive Staff' from the start.

I'm trying to find a way to add the item programmatically to avoid it throwing an error as the Combobox is set as TRUE for match required - if there is a simpler solution then I'm open to suggestions!