Archive of Our Own (AO3) is also a great place to look. It has a large collection of fanfictions. The tagging system on AO3 makes it easy to find exactly what you're looking for. So, if you want a specific type of story involving Little Mix and Fifth Harmony, you can use the tags to narrow down your search.
Another option is to check out some fan - run forums dedicated to Little Mix and Fifth Harmony. Sometimes, fans will share their own fanfiction or recommend good ones they've read on these forums. You might have to do a bit of digging, but it can be worth it.
The best chapter pointer here is Chapter 20, "Miss Su, your defense is somewhat clumsy". It opens with Several people turned their heads upon hearing the sound and saw three... and closes on So, he turned and questioned Jiang Li..
Chapter 904, "Welcome Young Master and Young Madam!", is the clearest early answer because it turns Yu Fei's situation into a concrete plot event.
Chapter 744, "Dig Three Feet into the Ground to Find Her!", is the clearest early answer because it turns Wen Jiaojiao's situation into a concrete plot event.
Chapter 877, "You Are Not the Real Jiang Li!", is the clearest early answer because it turns Xu Mei's situation into a concrete plot event. A useful checkpoint is the way the scene starts with The Gu Family values their reputation greatly and has a dedicated PR...
Chapter 813, "She Has a Child?!", is the clearest early answer because it turns Jiang Mingchuan's situation into a concrete plot event. The chapter turns that into something concrete by moving from In the past, he might have helped Meng WanZhi speak.
A practical answer is Chapter 3, because it turns the idea into a concrete scene. The chapter opens with Qiao was still annoyed at the attitude of this unknown girl when she heard..., adds pressure through So without a second thought, she blurted out a fierce challenge, "Fine, if..., and ends on.
Chapter 827, "Mystical Event Investigation Bureau", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Jiang Li's words indeed make sense.
Chapter 911, "You Have Three Children?", is the clearest early answer because it turns Aunt Wan's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Jiang Bufan stood still, with his eyebrows furrowed, as if he was...
Chapter 692, "My Ideal Type is Assistant He", is the clearest early answer because it turns Gu Shengrong's situation into a concrete plot event. The chapter turns that into something concrete by moving from Zhao Lang's gaze stayed fixed ahead as he gripped the steering wheel...
Chapter 904, "Welcome Young Master and Young Madam!", is the clearest early answer because it turns Jiang Shixu's situation into a concrete plot event.