Sub io()
      Dim rText As String
      Dim i As Integer
      Dim AllDataOtvet As String
        
      rText = "НАЧАЛО "
      For i = 1 To 5
          rText = rText & "Специально подготовленный фрагмент текста замены из нескольких строк общей длиной более 255 символов "
      Next i
      rText = rText & "КОНЕЦ"
        
      Call SetClipboardText(rText)
      AllDataOtvet = "^c" ' = Left(rText, 255)
        
      With ActiveDocument.Content.Find
          .ClearFormatting
          .Text = "*Otvetchikifull*"
          With .Replacement
              .ClearFormatting
              .Text = AllDataOtvet
          End With
          .Execute Replace:=wdReplaceAll
      End With
End Sub

Sub SetClipboardText(ByVal txt$) ' запись в буфер обмена
      '(c) заимствовано из http://excelvba.ru/code/clipboard
      With GetObject("New:{1C3B4210-F441-11CE-B9EA-00AA006B1A69}")
           .SetText txt$
           .PutInClipboard
       End With
   End Sub

'Запись в буфер обмена

             With GetObject("New:{1C3B4210-F441-11CE-B9EA-00AA006B1A69}")
                 .SetText AllDataOtvet
                 .PutInClipboard
             End With

     AllDataOtvet = "^c" ' = Left(rText, 255)
          
     With ActiveDocument.Content.Find
         .ClearFormatting
         .Text = "*Otvetchikifull*"
         With .Replacement
             .ClearFormatting
             .Text = AllDataOtvet
         End With
         .Execute Replace:=wdReplaceAll
     End With