Complex sentence: Sloane was working with 20th Century Fox to promote Rocky Horror Picture Show and these short films were first shown at The "Third Annual Transylvanian Convention" held in Anaheim, California was also the launching of the Rocky Horror sequel "Shock Treatment".
Split into simpler sentences: Sloane was working with 20th Century Fox to promote Rocky Horror Picture Show and these short films were first shown at The "Third Annual Transylvanian Convention" held in Anaheim, California. It was also the launching of the Rocky Horror sequel "Shock Treatment".