Another member of the Stefani-Shelton household is getting his musical start at Blake Shelton‘s Oklahoma Ole Red bar. During an event on Monday night (July 29), Shelton was onstage to perform at his bar — and he surprised the crowd by inviting his 15-year-old stepson, Zuma, to the stage. “Zuma Rossdale, everybody,” Shelton can be heard saying in the video below, as he vacates his barstool so that Zuma can sit down and play. Fans may recall that Gwen Stefani‘s oldest son Kingston also appeared onstage at Ole Red to make his performance debut last summer. But while Kingston’s musical style leane…