gnus threads

[John Russell]

I have been using and liking gnus as my news reader, but I am still
not entirely comfortable with the 'see a message once and never again'
behavior.  I have found the S-^ to see the refering article of the
current article and I can do that all the way to the top of the thread
(unless gnus says referring article can't be found which seems to
happen totally at random).  This is fine to find the top of a thread,
but how can I find an article on a different branch of the same
thread.  Let's say there were two replies to an origianl message, I'm
reading replies to reply 1, but I want to go back to an article that
was a reply to reply 2.  Is there a way to show all messages that
were ever anywhere in a thread?  I know that you can do C-u <return> to 
see all messages in a news group, but that seems like overkill.
Thanks.

John