Complex sentence: During the first three seasons, Phoebe is shown as the most rebellious and youngest of the Halliwell sisters, but later becomes the middle sister after Prue Halliwell is killed and the introduction of her younger half-sister Paige Matthews.
Split into simpler sentences: During the first three seasons, Phoebe is shown as the youngest and most rebellious of the Halliwell sisters. She later becomes the middle sister after Prue Halliwell is killed and the series introduces her younger half-sister Paige Matthews.