Option Explicit
Dim FSO As Object, oFolder As Object, StrFolds As String, wdDocSrc As Document, wdDocTgt As Document

Sub Main()
Application.ScreenUpdating = False
Dim TopLevelFolder As String, TheFolders As Variant, aFolder As Variant, i As Long
TopLevelFolder = GetFolder
If TopLevelFolder = "" Then Exit Sub
StrFolds = vbCr & TopLevelFolder
If FSO Is Nothing Then
  Set FSO = CreateObject("Scripting.FileSystemObject")
End If
Set wdDocSrc = ActiveDocument
'Get the sub-folder structure
Set TheFolders = FSO.GetFolder(TopLevelFolder).SubFolders
For Each aFolder In TheFolders
  RecurseWriteFolderName (aFolder)
Next
'Process the documents in each folder
For i = 1 To UBound(Split(StrFolds, vbCr))
  Call UpdateDocuments(CStr(Split(StrFolds, vbCr)(i)))
Next
Set wdDocSrc = Nothing: Set wdDocTgt = Nothing
Application.ScreenUpdating = True
End Sub
 
Sub RecurseWriteFolderName(aFolder)
Dim SubFolders As Variant, SubFolder As Variant
Set SubFolders = FSO.GetFolder(aFolder).SubFolders
StrFolds = StrFolds & vbCr & CStr(aFolder)
On Error Resume Next
For Each SubFolder In SubFolders
  RecurseWriteFolderName (SubFolder)
Next
End Sub
 
Function GetFolder() As String
Dim oFolder As Object
GetFolder = ""
Set oFolder = CreateObject("Shell.Application").BrowseForFolder(0, "Choose a folder", 0)
If (Not oFolder Is Nothing) Then GetFolder = oFolder.Items.Item.Path
Set oFolder = Nothing
End Function

Sub UpdateDocuments(oFolder As String)
Dim strInFolder As String, strFile As String, Sctn As Section, HdFt As HeaderFooter
strInFolder = oFolder
strFile = Dir(strInFolder & "\*.doc", vbNormal)
While strFile <> ""
  Set wdDocTgt = Documents.Open(FileName:=strInFolder & "\" & strFile, AddToRecentFiles:=False, Visible:=False)
  With wdDocTgt
    For Each Sctn In .Sections
      For Each HdFt In Sctn.Headers
        With HdFt
          If .Exists Then .Range.Find.Execute FindText:="[^13]{3,}", ReplaceWith:="^p^p", MatchWildcards:=True, Replace:=wdReplaceAll
        End With
      Next
    Next
    'Save and close the document
    .Close SaveChanges:=True
  End With
  strFile = Dir()
Wend
End Sub