Complex sentence: Judges Howie Mandel and Howard Stern returned for their respective fourth and second seasons, with Melanie Brown replacing Sharon Osbourne and Heidi Klum joined the judging panel as a fourth judge.
Split into simpler sentences: Judges Howie Mandel and Howard Stern returned for their respective fourth and second seasons. Following the departure of Sharon Osbourne, Melanie Brown joined the judging panel in her place and Heidi Klum joined as a fourth judge.