Who is XXX's sister?
Li Chongfu
In 701, Li Chongfu's brother Li Chongzhao (who had, by this point, changed his name to Li Chongrun to observe naming taboo of Wu Zetian's name), along with their sister Li Xianhui (李仙蕙) the Lady Yongtai and Li Xianhui's husband Wu Yanji (武延基) the Prince of Wei (Wu Zetian's grandnephew), were put to death for criticizing Wu Zetian's lovers Zhang Yizhi and Zhang Changzong.
Li Xianhui