To make sure The GiyuKana Twins; Giichi and Yumi are 15, the same age around Tanjiro and the squad,

I Basically have to make The Age Gap with the Pillars, Uzui wives and Ubayushiki parents, except for Muichiro, to be 9 years ahead.

Tomioka twins, Tanjiro and Inosuke= 15

Kanao, Aoi, Zenitsu=16

Muichiro and Nezuko= 14

(Canon pillar [-Muichiro] {Genya} age) 9 years

Genya=25

Giyu, Sanemi, Obanai, Hinatsaru= 30

Mitsuri, suma= 28

Shinobu, =27

Gyomei, Amane=36

Kyojuro,Makio=29

Tengen,Kagaya=32

Kanae dies at 21.

Kanao would get adopted at Age 6, while Kanae at age 20, and Shinobu at age 17

Kanao and Aoi at age 7(instead of 12)when Kanae dies from Douma.

When it comes to that, Kiyo, Sumi and Naho never met Kanae before.