Lol everyone getting creeped out🤣
Well in my religion its allowed for adoptive siblings to marry. Unless the child is under two and was weaned by the adoptive mother, then it won't be allowed.
The adopted sibling isn't regarded as an 'actual' sibling, especially after puberty. Doesn't mean they are treated any less than an actual sibling.
Imagine a childhood friend living with you since young.
And as I said before Eugene and Hari barely grew up together in both timelines. Only 2 years. Whereas she grew up with Johan for 6 years. And she's not a doppelganger of their late sister. Only her hair has a slight resemblance.