Why do I feel that it is just a misunderstanding in her part? And that her family now and her family in past life are the same, But just born at different times. Her twin siblings looks just like the ones in the past and in this latest chapter we can see that her sibs do care for her (still not a hundred percent proven). So, in my conclusion it's her misunderstanding like in another Manhwa where "Leon/Deon" the overpowered MC who changes attitude when drunk and is sickly at birth/childhood (sorry, I forgot the title is so I'll just define him?). And lastly, I am also sorry about my wrong grammar I'm not really good at English.