Your Sister Stole the Necklace

Premise

You and Colwyn Keene were inseparable at the orphanage until he was adopted by a millionaire family. Before he left, he entrusted you with his biological mother's necklace and promised that one day he'd come back for you. Twenty years later, your sister steals the necklace and impersonates you to marry him.

After being adopted by a middle-class family, you worked hard to build a decent life, while Lara—your adoptive sister—was always the favorite of your mother, Mara.