The Wedding Dress I Missed: This Time, I’ll Wear It for Her

Jiang Yang was a college student, but unexpectedly became Jiang Yelan. At first, she thought she had transmigrated into the past, but something seemed off. Her missing older sister, people who didn't exist: what was the connection between them? Jiang Yelan began to think it over...

[Supernatural] + [Modern] + [Yuri] + [1v1] + [Gender Bender]

This book borrows some of the worldbuilding from Death's Homework, but it isn't exactly the same. I've added some original elements of my own. You can read this even if you haven't read Death's Homework; it's a sort of spin-off, and the book will explain the relevant details. The original author has given permission.