The father of Chacha, Go, and Hatsu is one character who wasn't included: Nagamasa Azai
I've played many Samurai Warrior games, and am familiar with the whole series of events involving the Sengoku era of Japan (aprox. 1500-1600)
Oichi is slightly younger than Nobunaga. Matter of fact, I have a list of the main warlords, age wise.
In order of birth:
Kunoichi technically doesn't exist, and Kotaro's birthdate is unknown.
The infamous Honnoji incident, resulting in the death of Nobunaga, occurred in 1582. By that point, Motonori, Ujiyasu, Yoshimoto, Shingen, Kenshin, and Hanbei were already deceased.
At no point was every single person on this list alive at the same time.