Marshall told Spy she had always been a "shower singer". In 2005 she won the Sing Like a Superstar reality TV show.
"I've always enjoyed singing," she said. "Without really realising, Lucy and I have found ourselves singing at three different weddings. Requests from friends so far, but [we're] keen to get out there and do more. I went through a phase of singing at funerals. Weddings are a little more fun."
Lucy Ewen and Siobhan Marshall perform.
There are no plans yet for Marshall - who finished third in the Dancing With the Stars NZ reality TV show last year - to chase a professional music career.