Thanks but I believe the problem is that my process isn't right - not just the inputs.
I'm now looking at the Foundation->RepositoryService->Read Resource Content, Process Management->FormAugmenterService->Insert Workflow XFO Data, and Output->generatePDFOutput services.
Of course, the documentation is useless to everyone but the authors of the services. :-(
I've asked Platinum support to tell me outright if it can be done. It has been months and they've yet to say that they have any idea how to go about it.
In my opinion, it should have been as easy as ticking off a checkbox labelled: save a copy when the process finishes!