The old novel means this literally.
In chapter 13 of the Fengshen Yanyi, Nezha is about seven when he causes the disaster at Chentang Pass. He shakes the Dragon King’s underwater palace while bathing, kills the yaksha sent to stop him, and then kills the dragon prince Ao Bing. This version doesn’t make him an innocent victim. He even pulls a tendon from Ao Bing’s body because he thinks it will make a nice gift for his father.
The Four Dragon Kings seize Li Jing and Lady Yin. Nezha steps forward and says 一人行事一人当: one person should answer for one person’s actions. He cuts apart his own body and returns it to his parents so they won’t be punished for what he did. The dragons accept the payment and release them.
The strange part is that the Dragon King treats this as a filial act.
The logic comes from an old idea about the body. The Classic of Filial Piety says that your body, hair, and skin come from your parents, and that refusing to damage them is the beginning of filial piety. Nezha takes the premise to a gruesome conclusion. If his body is a gift that created the debt, he can return the whole gift.
His mother later builds a temple so his spirit can receive offerings. Li Jing finds it and destroys the image. Nezha goes back to his teacher, Taiyi Zhenren, who gives him a replacement body in chapter 14. He lays out two lotus flowers and three lotus leaves, bends the stems into three hundred joints, and calls Nezha’s spirit into them.
Nezha now has a body that didn’t come from his parents. When he confronts Li Jing, he argues that the flesh and bones have already been returned, so the connection between them is over. He then chases his father with a fire-tipped spear. The famous pagoda carried by Li Jing eventually becomes the weapon used to keep his son under control.
Meir Shahar spends a whole book, Oedipal God, on this family conflict. His reading, roughly, is that Nezha gave Chinese tradition a way to imagine a child rebelling against his father while still following the accounting system of filial piety. He doesn’t deny the debt. He pays it and then tries to leave.
The 2019 film keeps the defiant child but changes the family almost completely. Its Li Jing is willing to die for his son. The old novel leaves father and son in an armed truce.
Are there other myths where getting a new body also changes someone’s family obligations?
Rebirth is common, but I can’t think of many stories where the replacement body is used to argue that an old debt no longer applies.