VBA to expand a referenced range of cells

Hi all,

Looking for some help with my code.

Here is what I have:

A combobox that references a range of cells and that launches another UserForm when "Other" is selected:

Private Sub cmboProjectType_DropButtonClick()
    With cmboProjectType
        Me.cmboProjectType.List = Worksheets("Status Values").Range("C15:C17").Value
    End With
End Sub
Private Sub cmboProjectType_AfterUpdate() ' A solution for the "Other" problem. Pop up UserForm to fill
If cmboProjectType.Value = "Other" Then
    AddOtherValue.Show
End If
End Sub

And a UserForm that adds another value to the combobox:

Private Sub cmdOtherValueOK_Click()
ProjectInformationFormAlt.cmboProjectType.Text = txtOther.Text
Unload Me
End Sub

What I would like to happen is the following: When a value is added using the AddOtherValue UserForm it adds to the worksheet where the combobox is making the referenece (in addition to the combobox code that exists already). I would then like the range being referenced by cmboProjectType to expand by 1 (so that the next time this UserForm is launched it will show the new value that was added in the dropdown)

The easiest way I see to accomplish this is to have the range reference a value (say A3) and to keep referencing values in that column until it reaches a blank.

I am open to suggestions though!

Thanks in advance,

Wolf