Complex sentence: In the beginning, Opal was only supposed to remain on "All My Children" for about six weeks but, when the show's executives saw Dorothy Lyman's electric portrayal of the character, the writers kept her on and wrote for her more and more.
Split into simpler sentences: In the beginning, Opal was only supposed to remain on "All My Children" for about six weeks. But when the show's executives saw Dorothy Lyman's electric portrayal of the character, the writers kept her on and wrote for her more and more.