They were never related to each other in the first place, even before she took place of the "sisters" body they were never actually siblings. In the rumors we hear she's not blood related to him, that's why people were saying she cant be head since she doesn't have Lachia blood.
idk i dont rlly count step siblings as incest. I still dont like the whole siblings concept i find it a bit uncomfy even if they are not related.
yeas she never grow up with him either even if people want to say they "grow up together has brother and sister" the FL never did XD she come from another world and she is who is from that world. so nope they are not sister and brother in any shame or form. and ML does not see her has his sister from the start XD
Yall dumb asf there aren't even step sibling since this girl is from the modern world