The Mei Lan family's Clan Leader Chi Xun is Teacher Yirou's father, and since she is his only daughter, he dotes on her immensely. This was evident from the very beginning when he openly confronted the Phantom Spirit family for her sake.
Since Yirou had chosen to support Ye You and Qin Sisi, Chi Xun was initially hesitant, after all, looking at their current strength, this partnership seemed very weak.
Yirou appealed to her father emotionally and rationally, and finally persuaded him.
The Mei Lan family secretly purged Miaoyin City, discovering several undercover spies sent by Tian Xiaozi. Chi Xun silently eliminated those spies, causing Tian Xiaozi to lose many of his trusted generals without even realizing it.
As for Scholar City, it goes without saying. Tian Xiaozi's repeated attacks on students of the Heavenly Magic God's Castle had long infuriated Master Yipiao, resulting in even tighter security within Scholar City.