Beyoncé’s youngest daughter Rumi usually stays out of the spotlight, unlike her sister Blue Ivy. That made it all the more surprising when she suddenly appeared on stage alongside her mother during the opening night of the “Cowboy Carter” tour. Beyoncé Knowles, 43, kicked off her Cowboy Carter and the Rodeo Chitlin Circuit tour in California with a spectacular show. But the excitement wasn’t just about the superstar herself—her two daughters stole the spotlight. Both 13-year-old Blue Ivy, who already has stage experience from past performances with her mother, and