It appears he has earned his right to the spotlight. Hong Kong star Julian Cheung performed in Guangzhou, China, on Aug 22 and 23, and his band was joined by his son Morton. The 19-year-old, the only child of Julian and Hong Kong actress Anita Yuen, who both turn 55 this and next week respectively, made a surprise appearance as a guitarist. Clad in an unassuming all-black casual outfit, his attendance was confirmed when his name was listed in the concert's end-credits. Netizens also took videos where Morton is seen smiling and waving goodbye to the audience before going backstage. Anita had previously said he had no plans to enter the…