Move data from one list to another and back again

I have to list boxes, the user double-clicks to select an employee and this name shows up in the second list.  This works fine - HOWEVER, if the user needs to remove a name from the second list box (by double-clicking) , the name should move back to the first list box.  I have the code that moves the data from lstEmployees to lstAssignedTo, but if the user changes their mind, not sure how to do it in reverse.  The code uses a txtSelection control on the form to hold the userID's of those that have been selected, which is used in the underlying query to update the rowsource.

Sandra

Private Sub lstEmployees_DblClick(Cancel As Integer)
Dim strList As Variant
Dim ctl As Control
Dim varItem As Variant

    Set ctl = Me.lstEmployees

    strList = Me.txtSelection
   
    For Each varItem In ctl.ItemsSelected
        If IsNull(Me.txtSelection) Then
            strList = """" & ctl.ItemData(varItem) & ""","""
        Else
            strList = strList & """" & ctl.ItemData(varItem) & """" & ","""
        End If
    Next varItem
   
    Me.txtSelection = Left(strList, Len(strList) - 1)
   
    Call FctRefreshLists

End Sub
Public Function FctRefreshLists()
'The list box on the right will show only all items selected
On Error GoTo ErrorHandler
Dim strSelected As String
Dim strNotSelected As String
Dim intUserTeam As Integer
Dim strSQLNotselected As String
Dim strSelectedText As String

strSelectedText = Left(Me.txtSelection, Len(Me.txtSelection) - 1)

strSelected = ""

If Not IsNull(Me.txtSelection) And Me.txtSelection <> "" Then
    strSelected = "SELECT tblEmployees.EmpUserID, [EmpLastName] & ', ' & [EmpFirstName] AS EmpName " & _
        "FROM tblEmployees WHERE tblEmployees.EmpTerminated = 0 AND EmpUserID In(" & strSelectedText & ") " & _
        "ORDER BY tblEmployees.EmpLastName "
Else 'don't show any
    strSelected = ""
End If

Me.lstAssignedTo.RowSource = strSelected
Me.lstAssignedTo.Requery

'The list box on the LEFT will show only all items that are NOT selected
If Not IsNull(Me.txtSelection) And Me.txtSelection <> "" Then
    strNotSelected = "SELECT tblEmployees.EmpUserID, [EmpLastName] & ', ' & [EmpFirstName] AS EmpName " & _
        "FROM tblEmployees WHERE tblEmployees.EmpTerminated = 0 AND EmpUserID NOT IN(" & strSelectedText & ") " & _
        "ORDER BY tblEmployees.EmpLastName "
Else
    strNotSelected = "SELECT tblEmployees.EmpUserID, [EmpLastName] & ', ' & [EmpFirstName] AS EmpName " & _
        "FROM tblEmployees WHERE tblEmployees.EmpTerminated = 0" & _
        "ORDER BY tblEmployees.EmpLastName "
End If

Me.lstEmployees.RowSource = strNotSelected
Me.lstEmployees.Requery

Exit_ErrorHandler:
    Exit Function
ErrorHandler:
    MsgBox "Error Number: " & Err.Number & vbCrLf & _
           "Description: " & Err.description & vbCrLf & _
           "Function FctRefreshLists", vbOKOnly
    Resume Exit_ErrorHandler
End Function