I have a major Idea.
1) Use the universal Gundam Timeline that has all the cannon characters involved. It could take place in the far future were amuro, kira and all the main characters are now aged veterans of combat as a new group of pilots, captains,medics and mechanics arise as a new war between the Principality of Zeon and the Earth Federation begins due to old Rivalry or political unrest. It starts when The Allied space school ASTRAL Academy (in orbit around the planet earth) is invaded by both Zeon and Earth spies to gain intel on each other but when they both realise that they were both tricked into an alliance they begin the next war. As the neutral forces (formally known as the axis lead by Haman) try to stop the war between the two superpower forces.
With gundams stored away in ASTRAL some models were stolen by both sides for restoration and/or modification as the Alliance was left with only few gundams to suppress the war.
This also inculed all of the Lagragian points: (L=distance to earth) 1 closest to 5 farthest
L5:Zarn
L4:Hatte
L4:Riah
L3:Noa
L2 :Munzo
L1: Mua
L1:Laum
L1:Gaea
Each lagrangian point being an essential point in the war they should be spread out between the forces. 3 for Zeon 3 for Earth and 2 for Alliance. The alliance should control The Noa point due to it containing the the gryps colony cannon able to destroy an armada of MS including any Gundam in its path and the Munzo point it being a middle point as well. It also being the most middle point. Zarn, Hatte and Riah to the Zeon forces. Laum, Mua and Gaea for Earth. The Ocs should be able to take these points to win the war. But if your stationned at the L1 and zeon attacks the L2 you can`t just show up to defend it because the Lagrangian points are a fair distance away from each other. But the lagrangian points in the same sector (such as Hatte and Riah at L4 and Laum, Mua and Gaea at L1) can be travelled to and from easily.
There could also be a rogue group of titan pillots. and even though being in the official timeline it can still have the seireki and cosmic era timeline gundams.