Complex sentence: The film also featured the talents of singer/actress Erin O'Brien, whose singing performance as a singer required no dubbing; she appeared as a featured solo singer on six episodes of "The Steve Allen Show" during this same period.
Split into simpler sentences: The film also featured the talents of singer/actress Erin O'Brien. Her singing performance as a singer required no dubbing; she appeared as a featured solo singer on six episodes of "The Steve Allen Show" during this same period.