Since the Swans are described and portrayed as white, I decided to make Lizzy adopted so she can be any race or ethnicity. Also Leah isn't mentioned until New Moon. However, for the flow of the story, I decided to move her transformation to taking place before the events of the first book. Since this would make Leah and Lizzy seniors in high school, there will be a lot of gaps in the story for when Lizzy will go to college.
I haven't read the books (don't come for me I plan on reading them). I royally screw up the timeline. I rush through a few plot points because I don't want it to be too long for your sake and for mine. The timeline is sort of weird and screwy, I tried my best to make it cohesive. I tried to fix some of the more problematic story elements.
Also, the Quileute Tribe are a real Native American tribe who have a rich culture and history that Stephenie Meyer appropriated for the Twilight series. I do not agree with the way Stephenie Meyer handled the Quileute people, or the way she stereotyped her Native American characters. You can learn about and donate to the real Quileute people.
I also have a story where Seth imprints on a younger version Lizzy. Y/n version on Wattpad and AO3.