There's a fanfiction called 'Twinned in the Force' that is quite interesting. It explores the concept of twinning not just physically but also in terms of a connection in the Force. The characters' development as they come to terms with their twinned nature and how it affects their place in the Star Wars universe is really well - written. Also, 'The Twin Bond' is a great read, especially if you're interested in the emotional aspects of the relationship between the twinned characters.
I would recommend 'Twin Stars of the Galaxy'. This fanfiction takes two relatively unknown characters and makes them twins, and then weaves an exciting story around their discovery of this fact and their subsequent adventures. It has great action scenes and also explores the cultural aspects of different Star Wars planets as the twins travel through the galaxy. 'Twin Destiny' is also worth checking out. It has a unique take on the twinning concept, where the twins have opposing goals at first but then gradually realize they need to work together in the greater scheme of things in the Star Wars world.
Chapter 177, "You Annoy Me Just By Being Here", is the clearest early answer because it turns Jiang Yan's situation into a concrete plot event. The chapter turns that into something concrete by moving from I'm actually the last?!" After the scores were announced, Wen...
Chapter 345, "Audition: She Couldn't Have Gotten in Through Backdoor Connections, Could She?", is the clearest early answer because it turns Director Zhang's situation into a concrete plot event.
Chapter 243, "How Could It Be Her?!", is the clearest early answer because it turns Wen Jiaojiao's situation into a concrete plot event.
Chapter 475, "Doting on the Man You Love to the Fullest", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. The chapter turns that into something concrete by moving from On the other side, Jiang Yan and Shang Shuyue also set off.
Chapter 263, "Jiang Li Won the Medal for Outstanding Individual?!", is the clearest early answer because it turns Director Sun's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Southwest Wildlife Protection Association V: On the evening of July...
Chapter 48, "All the Bitter Teas Have Been Taken Away", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. The chapter turns that into something concrete by moving from He Yun felt guilty for initially ignoring Jiang Li on purpose, and...
Chapter 454, "Are these two people crazy?!", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. It opens with Shang Shuyue felt that following Jiang Li was the best decision she... and closes on Alright, next we'll go for training!" Yu Li: ?.
Chapter 288, "The Old Master Already Knows", is the clearest early answer because it turns Jiang Yan's situation into a concrete plot event. Early on, Jiang Li and Zhao Lang were lifted onto stretchers and taken to....
Chapter 168, "Gu Family in the Capital", is the clearest early answer because it turns Gu Yu's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Su Yinwan spoke those words with a pitiable expression, then lowered...
Chapter 213, "Shi Xu, You Must Understand How to Balance Meat and Vegetables", is the clearest early answer because it turns Aunt Zhang's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Jiang Cheng also noticed where Jiang Shixu's attention lay.