If you're absolutely set on using the news system you've already got, just make it have the link SirGrendel posted. If I were you, though, I'd make the topic yourself, and then make the link to where users can reply to it. Not have the users actually create the topic. If every user that clicks the link makes a new topic to discuss the same thing, it could get very confusing.
However, the way it's done on the UBBDev front page (afaik) is with the UBBNews hack, which brings in posts from a forum you specify via SSI. Therefore if you post a new topic in Forum 1, it brings that topic onto whatever page has the SSI call. And it's automatically got the reply link.
That is the way I'd recommend you do this. With the UBBNews hack, it would eliminate the need to post news in both your already-existing news system as well as the UBB. Just one less step to make your day a little more efficient.

---Skorpion