The Eldest Princess was actually in cahoots with the Second Prince in Joy of Life. Although she appeared to be deliberately getting close to the Crown Prince, making others think that she was on the same side as the Crown Prince, in reality, the Crown Prince was just a shield. The Eldest Princess had secretly colluded with the Second Prince. The two of them worked together to overthrow Fan Xian. This plot was revealed and hinted at in the TV series Joy of Life.

The answer to which chapter of Joy of Life was chapter 86.
In Joy of Life, the story of the Eldest Princess took place in chapter 86 of the sixth volume.
In Joy of Life, the scene of the Eldest Princess sacrificing herself to the Crown Prince happened in chapter 86 of the sixth volume.
Yes, the eldest princess in Joy of Life was the princess of the Qing Kingdom.
In Joy of Life2, the Great Prince was summoned back by the Qing Emperor and married the Great Princess of Northern Qi, making him Prince Heqing. The First Prince led the army to the west and won. He also brought the daughter of the leader of the Western Hu tribe, Ma Suosuo, back to his residence. However, the Great Prince did not cherish Ma Suosuo. He sent her to Baoyue Brothel in Jiangnan for Fan Xian to take care of. As for the plot of the eldest princess, the search results did not mention the specific plot development.
The Eldest Princess was a character in Joy of Life. She was the Qing Emperor's younger sister. Although she was not related by blood, she was given the title of princess because of the Qing Emperor's special love and trust. In ancient times, princesses usually had their own fiefs and special treatment. In the novel, the Eldest Princess 'fief was set in Xinyang. This was only the author's setting and had no special meaning. As the Qing Emperor's younger sister, the Eldest Princess had always been by the Qing Emperor's side to assist in handling affairs. Because she had special feelings for the Qing Emperor, the Qing Emperor also trusted her very much. In short, the Eldest Princess was a princess because of her identity and status.
In Joy of Life, the Eldest Princess and the Qing Emperor were siblings. They were half-siblings and had no blood relationship. The Eldest Princess loved the Qing Emperor deeply, but the Qing Emperor only treated her as a younger sister. The Eldest Princess was jealous and resentful of the Qing Emperor and Ye Qingmei's relationship. She secretly plotted to murder the Qing Emperor. However, the Qing Emperor saw through her plan, and in the end, the Eldest Princess committed suicide. As for whether they were blood-related siblings, the article did not explicitly mention it.
In Joy of Life's original work, the Eldest Princess and the Qing Emperor were siblings. In the story, they were half-siblings with the same father and were not related by blood. The Eldest Princess liked the Qing Emperor, and the Qing Emperor had special feelings for the Eldest Princess. There was a complicated emotional entanglement between them. The Qing Emperor tacitly approved of the Eldest Princess 'monstrous power, but when he learned that the Eldest Princess and the Crown Prince had an affair, the Qing Emperor was furious and massacred the Eastern Palace. The relationship between the Eldest Princess and the Qing Emperor experienced many twists and turns in the story.
During the Qing years, the Eldest Princess and the Qing Emperor were siblings, but they were not related by blood. The Eldest Princess loved the Qing Emperor deeply, but the Qing Emperor only treated her as a younger sister. The Eldest Princess was jealous and resentful of the Qing Emperor and Ye Qingmei's relationship. She secretly plotted to murder the Qing Emperor. However, the Qing Emperor saw through her scheme. The relationship between the Qing Emperor and the Eldest Princess experienced many twists and turns in the story.
In Joy of Life, the Eldest Princess and the Qing Emperor were half-siblings. They were not related by blood. The Eldest Princess loved the Qing Emperor deeply, but the Qing Emperor only treated her as a younger sister. The Eldest Princess was jealous and resentful of the Qing Emperor and Ye Qingmei's relationship. She secretly plotted to murder the Qing Emperor. However, the Qing Emperor saw through her plan. The Qing Emperor's feelings for the Eldest Princess were not as good as we thought. He valued Lin Ruofu more and even had a son with Ye Qingmei, Fan Xian. The relationship between the Eldest Princess and the Qing Emperor experienced many twists and turns in the story.
The relationship between the Eldest Princess and the Qing Emperor took place in the sixth volume, chapter 86, of Joy of Life.