Complex sentence: When MacDonald created the character, he was to be called Dallas McGee, after the city, but after the Kennedy assassination he decided that name had too many negative connotations.
Split into simpler sentences: When MacDonald created the character, he was to be called Dallas McGee, after the city. According to MacDonald, he had originally named the character Dallas McGee, but after the Kennedy assassination he decided that name had too many negative connotations.