IF you have a NT Security then you should not be doing anything but just open the Dashboard and it will do the Data Reduction on its own as the Document is opened with the Domain User.
IF you are not using NT Security then on the Actions Tab you can Open an URL, Use variables to pass the identity of the user while building the URL string.
Refer below link and see if it helps
Not sure if you got it working... why don't implement same Section Access on the QlikView2.QVW file? As per your question you have the same fields in QlikView2.QVW right. You can use document chaining and have Section Access on both the files.
I hope this helps!