Em folhas protegidas:
Cole o link abaixo na pasta de trabalho
Option Explicit
Private Sub Worksheet_Change(ByVal Target As Range)
Dim wsh As Variant
For Each wsh In Worksheets(Array("Sheet1"))
wsh.EnableOutlining = True
wsh.Protect UserInterfaceOnly:=True, Password:="", _
DrawingObjects:=False, _
Contents:=True, _
Scenarios:=True, _
AllowFormattingCells:=False, _
AllowFormattingColumns:=False, _
AllowFormattingRows:=False, _
AllowInsertingColumns:=False, _
AllowInsertingRows:=False, _
AllowInsertingHyperlinks:=False, _
AllowDeletingColumns:=False, _
AllowDeletingRows:=False, _
AllowSorting:=False, _
AllowFiltering:=False, _
AllowUsingPivotTables:=False
Next wsh
Dim Oldvalue As String
Dim Newvalue As String
On Error GoTo Exitsub
If Target.Address = "$C$2" Then 'As required
If Target.SpecialCells(xlCellTypeAllValidation) Is Nothing Then
GoTo Exitsub
Else: If Target.Value = "" Then GoTo Exitsub Else
Application.EnableEvents = False
Newvalue = Target.Value
Application.Undo
Oldvalue = Target.Value
If Oldvalue = "" Then
Target.Value = Newvalue
Else
Target.Value = Oldvalue & ", " & Newvalue
End If
End If
End If
Exitsub:
Application.EnableEvents = True
End Sub