The Clan Leader of the Fan Family must know what kind of people Fan Tong's mother and sister-in-law are.
But the core of this matter has nothing to do with the character of the mother-in-law and sister-in-law.
Old Mrs. Fan and the Fan Family's sister-in-law mistreating Gu Honglian doesn't mean they treat others in the clan badly.
Considering the status of daughters-in-law in their husband's families during these times, Gu Honglian's situation is too common. The clan leader would probably even think Gu Honglian is making a fuss.
They might even say, why hasn't any daughter-in-law in any family gone through this?
To put it bluntly, this is just a family conflict. Old Mrs. Fan and the Fan Family's sister-in-law could easily claim Gu Honglian is lazy, greedy, and unfilial, which would place them on the moral high ground.
Moreover, if even Fan Tong does not stand by Gu Honglian, who in the clan would dare to speak up for her?
