Sometimes rather than creating new PDF files every time, you want to scan to an existing document.
Over on the ScanSnap Community, they’ve posted a helpful video showing how to use Adobe Acrobat (which comes with the ScanSnap S1500) to scan to Acrobat and then add the pages to an existing document.
The video is below, but head on over to the Community for some restrictions and things to keep in mind.
If nothing else, watch the video for the swingin’ music.