Suggestions for adding footer to customer-provided PDF?

[brossow]

We are using iReport Designer 5.6.0.  We have a customer who has a set of T&C documents in PDF format and their legal team insists that they must be used exactly as provided, down to the exact word that ends a column/page, and so creating them as regular templates is out of the question.  The exception to this is that they ALSO must have a footer with page numbering added so that if a T&C document gets added to the end of a quote, the page numbering is continuous through the end of the generated PDF.

Aside from converting the various PDF pages to individual image files and inserting them into the template, is there any other way to take the PDFs as they are and just add page numbering?  I'm guessing not, but before I start the image conversion I thought I'd ask.  Any ideas are appreciated.