User blog comment:B214/High School DxD EX/@comment-1359322-20170414115452

Well since i already make the list from a discussion in animesuki. The sequence of Ise's children.

Kurenai > Airi > Zen > Shin > Helmwige > Ex > Robertina > Shirayuki & Kurobara

Quotes:
 * As for the last thing we discussed, it turns out that Kurenai is Ise's eldest son, and is eighteen years old. Zen is the second son at age seventeen. As for Ex, he is the fourth son of Ise's children.


 * "Likewise I am the son of the Sekiryuutei Hyoudou Issei and Shidou Irina——the third son named Shidou Shin."


 * "Kurenai nii-san is the eldest. The next one to be born was Airi nee-san. They were born in the same year. After that, there's myself, Shin, and one other who are the same age. The next youngest is Ex and one other person, and then after Ex it's Shirayuki and Kurobara."


 * “I am Helmwige. My father is the Sekiryuutei and my mother is a Valkyrie. I was born at the same year as Zen and Shin-kun.”


 * “That’s correct. I am the daughter of Hyoudou Issei and Ravel Hyoudou. I don’t use the Phoenix surname because mother left the house. Therefore, I use the last name father has been used in the underworld. I’m the same age as Ex-kun, by the way.”