Is the 'Piece' something that is a filemaker report or a PDF generated from a different source? If it is a filemaker report, they can use preview to "proof" it. If the PDF is generated from some other app, then you can store the PDF in a container field for them to open and preview (that's possible, in FMP 10, I don't know if FMP 8 can do this also).
I can think of two notification schemes:
1) a message that appears to notify the user that they have pieces to review when they open the file.
2) send them an email from filemaker notifying them.