merge

pdfunite in-1.pdf in-2.pdf in-n.pdf out.pdf
pdfunite *.pdf out.pdf
pdfunite $(ls *.pdf | sort -n) output.pdf - ordenado pelo nome dos documentos

http://stackoverflow.com/questions/2507766/merge-convert-multiple-pdf-f…

Sub MergeDocs()
Dim rng As Range
Dim MainDoc As Document
Dim strFile As String
Const strFolder = "C:\Book\Chapters\" 'change to suit
Set MainDoc = Documents.Add
strFile = Dir$(strFolder & "*.doc") ' can change to .docx
Do Until strFile = ""
Set rng = MainDoc.Range
rng.Collapse wdCollapseEnd
Selection.InsertBreak Type:=wdPageBreak ' inserir quebra de página
rng.InsertFile strFolder & strFile
strFile = Dir$()
Loop
End Sub