How do you work Split Analysis Collaboration?

So we have enabled the BU options to allow split analysis. We have set up several events where it's enabled but it seems all the dates entered during event creation are all for the collaboration on the event creation part. So when the event ends it says collaboration has ended but it wouldn't let us put dates past the preview date. In people books it doesn't give screenshots or instructions on how a collaborator would enter their scores so I'm not sure where to go at that point but I know as a collaborator if I enter the analyze page