Pokécharms

Here's how it'd work: First, we'd RP as OCs in the warrior unit with one person controlling General Magath (and probably another OC which would act as Zeke's replacement, and not necessarily inherit the Beast Titan, though they would still be able to if they liked). That person can then maybe assess each warrior candidate OC's skills and decide which titan they're most fit to inherit.

Then when we're done with that segment, we can orchestrate the attack on Shiganshina's walls and then introduce our Paradis OCs, their backstories and what happened to them during the breach. Then everyone enlists in the 104th and we continue on from there.

We might make changes in the plot as long as they make sense and are reasonable changes, for example killing off a character by having another inherit their titan and so on. Of course, the RP would be very spoiler-heavy so I'd recommend you catch up on AOT if you already aren't caught up, which I imagine many people already are.