FYI we had this issue to and this is how we set it up (works great!). Create custom properties for “Lead source” and “Lead description” and then we setup up those fields as drop down menus with the name of our shows pre-populated to avoid human error. We then select the type of marketing campaing event for the source, like “Booth lead” or “Hosted party event” and then in the description field we add the show name and year to the drop down list.