I know how to print multiple DataWindows in one print job:

Long ll_Job

ll_Job = PrintOpen("Transcript Report")
If ll_Job > 0 Then
    PrintDataWindow(ll_Job, dw_1)
    PrintDataWindow(ll_Job, dw_2)
    PrintClose(ll_Job)
Else
    MessageBox("Print", "PrintOpen Failed!", StopSign!)
End If

I also want to be able to save multiple DataWindows to one PDF file.

I was able to work out the following:

Print the DataWindows to postscript files.

Run the Ghostscript program with the right parameters to create a PDF file from the multiple .ps files.

I am wondering if anyone has had success doing this with NativePDF or some other method.