Based on the discussion, PW and SD have the same functionality. When I referred to adding PDF's to the chart as Attachments, I was referring to a functionality very similar to the SD Document Tree mdunham referred to. The PDF's do not show as thumbnails where images are displayed. My apologies for the confusion.
Seems to be a lot of interest in this topic. Hopefully SoftDent will take notice and add this functionality. Seems awfully 20th century not to be able to