I learned that most of the Gundam fans inspired and develop their own side story ideas such as GTFour Gundam and plenty more stories that isn’t really official. If you like to create one or more, you can name it.
I’ll go first,
Mobile Suit Gundam: Stardust Destiny
Nina Pupleton(Kou’s wife)
Linn Kajima(Yuu’s sister)
Captain Flint Deharka
Kirios Garrison(Zeon army, late Gato’s friend)
and more character is unidentified…