I don't think you could call the Phoenix a sister boat to the Dingo.

The Thai (16-foot), the Phoenix (18-foot), and the Shark (20-foot) all came about 10 years before the Dingo (15-foot). And while the first three were built in England as well as North America, I think the Dingo was only built by Gibbs in the U.S. (somebody correct me if that is wrong).