Attach Interactive Forum to Workflow from a Webdynpro ABAP application

I have a webdynpro ABAP application which has an Interactive form. After the user enters the form and clicks on 'Submit', I trigger a workflow for Approval. My requirement is to add this same form as an attachment to the workflow. I know I can do this by adding the Fileupload UI element and letting the user browse to the file after saving it. But I want to attach it directly without the user having to save the form to Desktop first.

I tried passing the pdf_source(XSTRING) to the container and it does attaches a pdf to the workflow but when I open it, the form is blank and user entered values are missing.

Please respond only if you know the solution and don't send me links to other forums on SDN, I have read them all.