About Kim Family,

Taeyeon’s father and Yuri’s mother are siblings and Taeyeon’s father is older.
Taeyeon’s father died in car accident when Taeyeon’s is 5 years old.

Yoona is not the real daughter of Taeyeon’s stepmother.
Actually, Yoona is the daughter of Taeyeon’s real mother.
So, Taeyeon and Yoona are not half-sisters. They’re real sisters.

But no one know about the truth, only their grandfather, their stepmother, their dead father, their missing mother, Yuri’s parents, Yuri and Yoona.
Their grandfather not let them to tell the truth to Taeyeon.

Yuri is a cousin of Taeyeon and Yoona.
She doesn’t really like her grandfather because of hiding the real identity about Yoona to Taeyeon.

Taeyeon lives alone by herself in a condo.
Yoona is living with her grandfather and (step)mother at the mansion.
Yuri is living with her parents.

About Jung Family,

Well, yesterday in my update there’s a typing error about Jung’s family.
I wrote that Jessica’s mother, Tiffany’s mother and Seohyun’s mother are sisters. And that is wrong. I will explain now.

Jessica’s father is the eldest in Jung family follow by Tiffany’s mother and Seohyun’s mother.
Jessica’s mother died in car accident.
Jessica has a younger sister named Krystal, who has diagnose with heart problem.

Tiffany is only daughter in her family and so as Seohyun.
And they all are staying with their family together like Jessica with her father and sister in one mansion, Tiffany with her parents in one mansion and Seohyun with her parents in one mansion.

Well, i'm doing my best on my next chapter.
Sorry for disappointing you guys by adding just about thier family.
Comments please :)
I'm waiting for you guys comments.