Exclusive: Mother Gives Stella a Sister... and an Impromptu Wedding?

I now present to you People's Exhibit J supporting the theory that Sarah Chalke's Stella is How I Met Your Mother's titular propagator: A wedding is on the way.Let me backtrack a bit. Sources tell TVGuide.com exclusively that Sara Paxton (Summerland) has been cast on the CBS sitcom as Nora, Stella's sister. Stella's bride-to-be sister. Except that the wedding doesn't seem to take. For Nora and her beau, at least. Seeing as the big day is all paid for and whatnot... I'm hearing that Stella decides to seize the moment and elect to walk down the aisle herself, with Ted awaiting her at the other end of the runner.Will the new season's Episode 5 tell the story of "How I Met Your Mother at the Altar"? Will Ted and his dermatologist sweetheart actually exchange "I dos"? Look for that answer during or before November sweeps. — Matt MitovichCrave scoop? E-mail Matt and Mickey at megascoop@tvguide.com.Related:• Regis Philbin to Guest on How I Met Your Mother • Mega Buzz on How...