Instead of spending a lot of time figuring out how to manually merge the databases for worlds, and how to equitably compensate the companies that won’t be in charge on the new world, how about this idea.
For each region, look at the total population and decide how many worlds you need to divide that between to have a “healthy” population on each. Then, create that many brand new worlds for that region, tell everyone in the region that you have two weeks to use the existing server transfer mechanism to shift to one of those new worlds from your current one, and just use that existing capability to handle the shifts. At the end of two weeks, anyone that still hasn’t moved, the next time they get on, they MUST pick one of the new worlds to go to, and then delete the old worlds. Everyone gets exactly what they get for shifting servers, no one gets compensated for not being in charge. Everyone starts at a clean slate, and the companies can fight out control on the new worlds.
The other benefit of this is you don’t have to deal with the inherently buggy process of merging two very complex databases. As someone that’s had to do this in the past, no matter how well you plan and how much you think you have it all figured out, somethings going to go wrong and pointers/keys will get messed up and you’re right back to the “my such and such weapon/armor is gone” or “changed to so and so”.
Yet another benefit of this is that you don’t have to deal with iterative merges for the tiny population servers. Example: Servers A, B, C and D all have tiny populations. Under the current plan, they’d merge A&B and C&D, then would still have to merge those two into a single one. Under this proposal, you’d create a new world, E, and force all the players on those 4 worlds to shift to it. Problem solved.