Hi Ernst,
You might want to ask this in a slightly different way in the Business Workflow forum to get a workflow perspective as well. Number one rule is: if you can change data in my system by whatever method you need to be identified.
But there are options around that.
Actually now I'm typing... one option is the BPM option to send an Adobe form to an email address. The user completes the form and presses a button on the form that returns it to the next step of the process. That's one to ask in the Business Process Management forum ... you would need a Process Orchestration (think of it as the new and improved version of what used to be PI).
Definitely an option if you already have that server and some PI skills at your site
Rgds,
Jocelyn