Generate and merge PDF

Hi,

I have a complicated task I need to resolve with LC.
First of all, I need to have a process, that on the invokation over WSDL will take document variable and convert that file to PDF.
Once this is done, I need to inject the PDF with process fields so I can have route names taks buttons in the workspace.
Once that is done, I need the user to be able to click on the route name button and the workflow should continue that way.

What I have done far:
- I can convert any doc to PDF (using the sample that comes with the LC)

What I need to do:
- insert process fields into the PDF (as far as I know, this can not be done, so I need to merge the converted PDF with blank PDF that has these process fields included)
- make sure, that the document is routed through route that the user picked by the button click (I did create flat PDF with process fields, I did use the form injection action to enable buttons in the workspace, however if I click on them, nothing happens. The task is still at assigned users workspace)

Any advices are highly apprecitated

J.