Merging PDF's in multiple locations with pdftk - vbscript

Question

I'm trying to merge multiple PDF's calling pdftk from a batch or VBS script file.
The issue is that the PDF's are all located in subfolders within a common parent directory. Example: parent folder > subfolder1, subfolder2, subfolder3, where the script/BAT file is located in parent folder and each subfolder contains a PDF.
pdftk is called as follows: pdftk.exe *.pdf cat output OutputFile.pdf
This will merge only the PDF's in the current directory though, and not in the subfolders.
Is there a way to do one of the following:
Use the VBS/BAT file to copy all PDF's in the subfolders to another directory, and not error-out if some of the subfolders are empty
Have pdftk look through the subfolders to select the PDF's to merge
Any help would be appreciated.

Answer 1

Try this:
Wscript.Echo "begin."
Dim pdffiles
pdffiles=""
Set objFSO = CreateObject("Scripting.FileSystemObject")
Set objSuperFolder = objFSO.GetFolder(WScript.Arguments(0))
Call ShowSubfolders (objSuperFolder)
Dim objShell
Set objShell = CreateObject("Shell.Application")
objShell.ShellExecute "pdftk.exe", pdffiles & " output combined.pdf", "", "runas", 1
Wscript.Echo "end."
WScript.Quit 0
Sub ShowSubFolders(fFolder)
Set objFolder = objFSO.GetFolder(fFolder.Path)
Set colFiles = objFolder.Files
For Each objFile in colFiles
If UCase(objFSO.GetExtensionName(objFile.name)) = "PDF" Then
pdffiles=pdffiles & " " & objFile.Name
End If
Next
For Each Subfolder in fFolder.SubFolders
ShowSubFolders(Subfolder)
Next
End Sub