From the hints dropped by Zhang Chongyang earlier, it was at least certain that there would be three factions involved: one trying to abduct the sovereign, another attempting to assassinate him, and a third aiming to protect him. Although Zhang Chongyang had arranged for people on all three sides, when it came down to a fight, it made more sense to place the heavy bet on the chess piece with the greatest odds of winning. This was probably also the reason he sought to recruit Li Fan.
After all, from the standpoint of the Three-yuan Taifu Mansion, it would be most beneficial to invite the Xun sovereign over for a visit since, with so many princes and grandsons in Xun Country, it didn't matter which royal successor or Prince Lu it was; as long as the Xun sovereign himself fell into their hands, no big waves could be stirred up. The new sovereign who emerged from the struggle would have to come and bow to the Three-yuan in Shangluo, seeking support to secure his reign.