Capturing Lead Source for Each Event

[Anonymous]

Sorry for not completely understanding. Our analytics person wants access to the source for each webinar for a lead - and I'm not exactly sure how the approach would accomplish this. Would we look at the activity log to see when this field changed? Here's an example of a user case:

I register for Webinar A through our website as the source. I then register for Webinar B coming from an Email. I then register for Webinar C coming from an external source.

For reporting, we want to compare the different sources for each Webinar. For example, seeing that our website source for webinar registrations was X for Webinar A and Y for Webinar B. 

[Anonymous]

I see now...thinking.

[Anonymous]

Any updates on URL parameters? Can I still only use them through form submission? I've finally got the team adding them to every single email and I'd like a scalable/efficient way to track sources of all clicks.