Ministers headed by imperial clan minister Zhao Ruyu (the descendant of the eldest son) and consort minister Han Shuazhou invited Queen Wu and directly adopted Song Guangzong's son Jia Wangzhao as emperor without the knowledge of those who refused to attend the funeral in the harem.
Zhao Kuo succeeded to the throne as Song Ningzong, but his father, Song Guangzong, involuntarily became the emperor's father. In short, he was deposed by courtiers, which made him the only emperor in the history of Song Dynasty who was forced to abdicate (if not counting Song Qinzong who was taken away during the Jingkang Revolution).
From the emperor's point of view, Song Guangzong was miserable. Everyone knows the difference between the emperor and the emperor's father. One has the right and the other has no right. There are three main reasons why Song Guangzong was deposed by the princes and the Empress Dowager. First of all, he is ill. Secondly, he is unfilial and refuses to serve the emperor's father. Finally, his wife Li Xinyu abused her power, which worried the ministers.
In addition to these three reasons, Song Guangzong was forced to become the emperor's father, which was closely related to the dispute between the Crown Prince and the Crown Prince at that time. Song Xiaozong had three sons, but Zhao Yun, the eldest son, and Zhao Kai, the second son, both died young. Therefore, when he didn't want to be emperor, he had to give up the throne to the only surviving third son, namely Song Guangzong.
Song Xiaozong abdicated and became the father of the emperor. He wanted to intervene in the affairs of succession to the throne after Song Guangzong. Song Guangzong and Li Xinyu had a son, who was later Zhao Kuo of Song Ningzong. This is Song Guangzong's only son and his first son. Anyway, the future throne is his.
But Song Xiaozong loved the son of Zhao Kai's second son, Zhao Kai (when he was in Zen, he intended to pass the throne directly to this grandson), hoping that Song Guangzong could make this grandson a crown prince. This is the root cause of Song Guangzong's disagreement with Emperor Tai-huang and Song Xiaozong after he succeeded to the throne.