How to represent this relationship in DataMapper

[eluser]papercut[/eluser]
Hi,

I'm using DataMapper with CodeIgniter and I'm having problems representing this relationship between two entities — Session and User.

- A Session has 1 author (User);
- A Session can be accessed by many Users.

I can successfully implement the first relationship alone, without the need of a join table, and I can also implement the second relationship alone, with a join table. But I can't get the two working at the same time.

How should I define them?

Thanks!