Associating pieces of data to a single interaction

We have an app where a user can select documents via checkboxes and then press a btn to email a list of links. I'm basically faking an array in Launch and storing the titles and then writing them out in custom code when the user presses the button. But now there's a requirement to capture department, so that they can do analytics on what documents each department is sending. If I also pass department (which I'm already capturing in a data element) in the same loop as I go through the array of documents will that department value then be associated with that specific document on the reporting side? They want to drag the document title dimension and they drop department underneath to see which departments used that document. Any thoughts? I feel like I'm missing some basic way in which Launch/DTM and Analytics works...