Secretly Married As the CEO's Substitute Bride

Her sister's fiance was said to be dead in an accident, but her parents won't give up on this marriage for their own benefits.
Of course, they won't sacrifice her sister - she's always the favored daughter. But as for her, well, they never cared for her.
That's how she became a substitute bride for her sister, marrying a dead person.
Until she finds out... he wasn't dead at all!