 Originally the main character, Sam, was going to be an electrician  and that is why the title was Sparkle. (In the UK, a sparky is a  nickname for someone in that profession.) However over time the plot  developed and Sams character was just looking for any kind work  when he went to London. The producers however still wanted to call  the film Sparkle, so had to come up with another reason for that.  They gave Sam the surname Sparks, and developed his mums character  as a singer, so that they could continue to use Sparkle as the  films title.