The Zong Family's Third Elder indeed contended with Mu Beichen for the position of Family Head and failed. The disharmony between the two factions was an open secret of the family.
As time passed, Mu Beichen grew older, and his only son, Mu Rui'an, had gone far away to Heishi City. Although Mu Beichen held the title of Family Head, the strength of his faction had weakened to an extreme.
In contrast, Mu Chengxuan was taken in by the Supreme Elder, regarded as a prodigy of the Mu Family. The Third Elder's faction was already strong, and with this, they were rising even more.
If things continued this way, it wouldn't be surprising if the Third Elder snatched the position of Family Head from Mu Beichen's hands.