bbPress.org

I think you could do something like this:

https://bbpress.org/forums/topic/wordpress-bbpress-register-plusgtgtgtgt

There are two different solutions there.

To redirect the member back where they came from after they’re done, you could do this:

https://bbpress.org/forums/topic/heres-a-trick-to-redirect-user-back-to-topic-after-login#post-14268