Complex sentence: Gein, who had been hospitalized after his fourth heroin overdose, was not invited to participate, and was fired from the band soon after, replaced by White, of Amboog-a-Lard, who undertook the alias Twiggy Ramirez.
Split into simpler sentences: Gein, who had been hospitalized after his fourth heroin overdose, was not invited to participate. He was replaced by White, of Amboog-a-Lard, who undertook the alias Twiggy Ramirez.