Yangtze River and the Huai River. Song sent the imperial censor Xiao Yinzhi () to the region to be in charge of collecting the damaged coins and taking them out of circulation. Xiao was strict in his behavior, drawing much resentment. Emperor Xuanzong, when he heard this, demoted Xiao, and in spring 720 removed Song and Su from their chancellor posts, giving Song the honorific title of Kaifu Yitong Sansi () instead. He replaced Song and Su with Yuan and Zhang Jiazhen. In 722, while Emperor Xuanzong was at Luoyang, there was a coup attempt at Chang'an by the army officer Quan Chubi (), who had his nephew Quan Liangshan () claim to be the son of Emperor Shang and therefore deserving of the throne. The coup attempt was put down quickly, and Quan Chubi was killed. Emperor Xuanzong sent the mayor of Hunan Municipality, Wang Yi (), to Chang'an to investigate. Wang detained a large number of people but could not quickly come to resolutions as to who were responsible. Emperor Xuanzong made Song in charge of Chang'an and had him investigate. Song quickly determined who were the leaders and had them executed, and at his request, Emperor Xuanzong pardoned the rest of the detainees. In 724, when Emperor Xuanzong was set to visit Luoyang again, he again made Song in charge of Chang'an and made him minister of civil service affairs; he also awarded Song with silk. Around 725, when Emperor Xuanzong's trusted general Wang Maozhong () was set to have his daughter married, he invited the key government officials to the wedding banquet—but Song declined; Wang, who wanted the honor of Song's attendance, had Emperor Xuanzong order Song to attend, which Song did, but as soon as he had the chance to toast the emperor, he then claimed illness and left the banquet. In 729, Song was made You Chengxiang (), one of the heads of the executive bureau of government (尚書省, Shangshu Sheng). The day that Song was to take office, Yuan and Zhang Shuo were to take new offices as well, Emperor Xuanzong set up a grand ceremony for their inauguration, including an elaborate tent, music, and food from the imperial kitchen. Emperor Xuanzong personally wrote a poem commemorating the contributions of the three. In 730, when the chancellor Pei Guangting took the office of minister of civil service affairs as well, Pei instituted a