But i think they're were acquainted because of their parents how to explain it FL's mom divorced and had multiple relationships before moving in with ML's dad (like the maternal relationship is much further than SAL) not sure if they got married or not but because FL and ML go to the same school they had more interaction even if it was brief, they weren't close but ML was older than her and kind of took care of her even that's why in the synopsis it's said they had to depend on eachother. It's not really step-siblings but I personally still consider it step-siblings hehe
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