How did Nancy Marchand appear on the Sopranos after her death?

Nancy Marchand, who played Livia Soprano on "The Sopranos," passed away in 2000 before the show's final season. To include her character posthumously, the show's creators used a combination of previously filmed footage and digital manipulation. They blended her existing scenes with new dialogue recorded by a voice actor, allowing her character to appear in the series while paying homage to Marchand's iconic performance.