Sub Macro1()
Dim oSection As Section
Dim oFooter As HeaderFooter
Dim oRng As Range
    For Each oSection In ActiveDocument.Sections
        For Each oFooter In oSection.Footers
            If oFooter.Exists Then
                Set oRng = oFooter.Range
                With oRng
                    .Collapse 0
                    .Fields.Add Range:=oRng, Type:=wdFieldIf, Text:="{PAGE} = {NUMPAGES} ""last page""", PreserveFormatting:=False
                    .Collapse 1
                    .MoveEndUntil "}"
                    .End = .End + 1
                    .MoveStartUntil "{"
                    .Text = ""
                    .Fields.Add Range:=oRng, Type:=wdFieldPage, PreserveFormatting:=False
                    .Collapse 0
                    .MoveEndUntil "}"
                    .End = .End + 1
                    .MoveStartUntil "{"
                    .Text = ""
                    .Fields.Add Range:=oRng, Type:=wdFieldNumPages, PreserveFormatting:=False
                    .Fields.Update
                End With
            End If
        Next oFooter
    Next oSection
lbl_Exit:
    Set oSection = Nothing
    Set oFooter = Nothing
    Set oRng = Nothing
    Exit Sub
End Sub