Try this in the code behind the worksheet...

Option Explicit

Private Sub Worksheet_Change(ByVal Target As Range)
If Target.Count = 1 Then
If Target.Column = 8 Then sub1_Change Target
If Target.Column = 11 Then sub2_Change Target
End If 'Target.Count = 1
End Sub


Private Sub sub1_Change(Target As Range)
' Description of what this does goes here...

Dim sOldVal$, sNewVal, lCode&
Dim rngDV As Range, rngList As Range, rngListID As Range

With ActiveSheet
Set rngList = .Range("external")
Set rngListID = .Range("externalID")
End With 'ActiveSheet

'On Error Resume Next
Set rngDV = Cells.SpecialCells(xlCellTypeAllValidation)
If rngDV Is Nothing Then Exit Sub

On Error GoTo exitHandler
If Not Intersect(Target, rngDV) Is Nothing Then
Application.EnableEvents = False
With Target
sNewVal = .Value: Application.Undo
sOldVal = .Value: .Value = sNewVal
If sNewVal = "" Then .Offset(0, 1).ClearContents
End With 'Target
With rngListID.Range("A1")
If Not oldVal = "" Then
lCode = .Offset(WorksheetFunction.Match(Target.Value, rngList,
0) - 1, 0)
Target.Offset(0, 1).Value = lCode
Else
lCode = .Offset(WorksheetFunction.Match(Target.Value, rngList,
0) - 1, 0)
Target.Value = sOldVal & ", " & sNewVal
Target.Offset(0, 1).Value = Target.Offset(0, 1).Value & ", " &
lCode
End If 'Not oldVal = ""
End With 'rngListID.Range("A1")
End If 'Not Intersect(Target, rngDV) Is Nothing

exitHandler:
Application.EnableEvents = True
End Sub

Private Sub sub2_Change(Target As Range)
' Description of what this does goes here...

Dim rngDV As Range, sOldVal$, sNewVal$

Set rngDV = Cells.SpecialCells(xlCellTypeAllValidation)
If rngDV Is Nothing Then Exit Sub

If Not Intersect(Target, rngDV) Is Nothing Then
Application.EnableEvents = False
With Target
sNewVal = .Value: Application.Undo
sOldVal = .Value: .Value = sNewVal
If sOldVal < "" Or sNewVal < "" Then _
.Value = oldVal & ", " & newVal
End With 'Target
End If 'Not Intersect(Target, rngDV) Is Nothing

exitHandler:
Application.EnableEvents = True
End Sub

--
Garry

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