Dim oRng As Range
Set oRng = Selection.Range
With oRng
    .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