Around 3 years ago, I wrote a crossover fic between reincarnated Kanae and TMNT 2014. It's simple and straightforward, but if I ever were to rewrite it, I probably would try to dive in more with Kanae's trauma and her sister-relationship with the turtles (missing your little butterfly girls? No worries, adopt mutant turtles instead!)
I would start with Kanae's second life parents involved with the Renaissance Project so Kanae and April knew each other. Then Kanae meets up with young turtles and they grow up together.
Why did I do this story? Just for funsies :3
(gonna link Kraang's involvement too tho)