Psycho Obsessed Dwarfs Stepbrothers and Cute Snow-white Little Sister (BTS FF)

An innocent cute girl named Bae Yn. her past is such a horrible then also she make everyone smile too. She have cute boxy smile and gummy smile which will melt everyone. She don't know about her father but still she loved him.

BTS Psycho powerful Mafia group members they all are siblings they are cold,rude and merciless to everyone except their loved ones.

How will they get to know that their parents are going to marry each other??
Will they accept each other??
Will they become obsessed her??