Complex sentence: He retrieves Nagato's Rinnegan to replace his replacement Sharingan, Tobi converts the reanimated corpses of the captured Jinchuriki into his personal Six Paths of Pain so he can use the captured Tailed Beasts' power through them.
Split into simpler sentences: He retrieves Nagato's Rinnegan to replace his replacement Sharingan. He also converts the reanimated corpses of the captured Jinchuriki into his personal Six Paths of Pain so he can use the captured Tailed Beasts' power through them.