A computer-based method for media composition of a family of related time-based media programs. The method involves creating a master program with time-based elements of video and/or audio as well as time-based and non-time-based metadata, creating a derivative program that includes derivative elements, defining an inheritance relationship between the master program and the derivative program that specifies elements of the master program to be inherited by the derivative program, and causing the derivative program to inherit the specified elements from the master program in accordance with the inheritance relationship. User interfaces are provided for creating, editing, and viewing hierarchical trees of related programs.