Wu Chengsi
As of 691, during Wu Zetian's reign, Zhang Jiafu was serving as "Fengge Sheren" (鳳閣舍人), a mid-level official at the legislative bureau of government (鳳閣, "Fengge"), when he was involved in instigating a petition drive led by Wang Qingzhi (王慶之) to persuade Wu Zetian to make her nephew Wu Chengsi the Prince of Wei crown prince to displace her son Li Dan, who was emperor from 684 to 690 until Wu Zetian took the throne herself. The petition drive initially got Wu Zetian's attention, and the chancellors Cen Changqian and Ge Fuyuan were executed for vehemently opposing it. However, she never made Wu Chengsi crown prince, and after Wang was killed by the official Li Zhaode later in the year, the petition drive dissipated.