Experience proved that nothing is impossible with enough effort.
After Jiang Cheng demanded "If Liu Qing doesn't go, neither will I," the Tongtian Sect's Liang Kingdom subrudder immediately convened a brainstorming session.
The topic of the meeting was how to bring a female cultivator with average talent, no distinguishing features, and not even part of the Tongtian Sect's system into their ranks.
Jiang Cheng, at least, was a university student with a special talent for talismans, a model for an elite disciple with no issues. Liu Qing, on the other hand, was a blank slate, just like when Jiang Cheng first recruited her, one of the those who knew nothing and had no background.
In the end, it was Dean Jian, a man of vast experience, who proposed a feasible plan— a "family visit visa."
Jiang Cheng's requirement was to bring Liu Qing into Tongtian Sect, not to have her accepted as a disciple.