Internally there is a "stanceLink" in the argument's SQL table.  My thoughts were to have it be able to link the outcome of a debate to an argument in some other debate.  Whenever the outcome of the linked-to debate changes, the score of the argument would then change.  I never implemented the frontend to it, however.
I havn't worked on debatepoint in a long while.  I was planning on migrating from php to python/django once I get 
Argon Project working.