Only track activity if visitor finishes first event

This is the flow:

People come to the site. They either fill out a submission form on the first page with their email or they leave.

The first event is submitting out submission form. If they do, they go more into the site and a few pages later they finish the 2nd event. I ONLY want to track the people who finish the first event, and I want that first event, the second event and the landing page.

If they do not fill out the submission form, I don’t want to pay for them as a session (don’t track em)

**Even better is if they are only tracked if they finish the SECOND event, and I then can get their landing URL and the first event. And not pay for tracking them if they do not do the second event (if this is possible, it would be best. It would require retroactive tracking. In other words, they get to the second event, they do the event, and then I get the past data that I set for them. If they do not do the second event, I don’t want to pay for tracking them, not interested in them).