Since a lot of you are confused ,lol. I wrote the character list.

Lee Sungmin - 41 years old.

He has 3 children (Taemin, Kris and Sunny). He was married to Sooyoung but she died. He is from a poor family. He is in SJ band.  He met Kyuhyun when the younger guy joined the band. (He hate it him at first because he thought Kyuhyun is trying to steal his spot in the band).     Cho Kyuhyun - 35 Years old He is from Giroux family ,The third rich family in Seoul.(only rich families are called by that name , and people are honored to marry into one of these families) He is Sungmin's ex In SJ band He has no kids , although he Consider Sungmin's kids as his.  

Lee Taemin - 24 years old.

Sungmin's first child.

Sooyoung got pregnant when she was 15 years old by mistake.(he is the reason they got married)

He is Minho's soon to be husband.

Lee Kris - 21 Years old

Sungmin's second child.  

Lee Sunny - 20 Years old

Sungmin's Third child.   Choi Siwon - 56 Years old From Giroux family(Thy are the first rich family in Seoul) Minho's Father Jessica's husband They have three children(Onew , Suzy and Minho)
Choi Jessica- 56 Years old. Siwon's wife

Choi Suzy - 27 Years old

Siwon and Jessica's first child.

Minsung's wife.( She is a lesbian)

Choi Onew - 26 Years old

The second child of the Choi family.

Marrie