Before reading underneath story my question is : how to show a webpage within a form? I downloaded the URL redirector widget and embedded it within a separate row of a template grid. Too bad, the url redirector redirects the total page rather than displaying a webpage within the specific region. Afterwards I downloaded the "form in form widget" and embedded the form with the URL redirector as a subform. In this way one would think the redirect would only work within a specific region. But again, the URL redirector truly redirects the whole page.
You can try using the HTMLSnippet widget or the iFrame widget from the AppStore. The iFrame widget reads the URL from an entity attribute, whereas the HTMLSnippet widget lets you type your own HTML code to display (so you could use it as a mini-redirect ;) )