Building a Dashboard for MQL and SQL Attribution by Channel

Hi folks - question around attribution. I'm looking to build a simple dashboard for marketing to see how many MQLs / SQLs are being driven per channel by month, using last touch attribution. Would like to also reflect, but not double-count, any activity that can be attributed to a given channel that isn't last-touch (e.g., an SQL is flagged as coming from a webinar but they got to the webinar via PPC). How would you typically indicate that in a dashboard?