The fusion of two Earths was not as simple as stacking them together, because that would have created far too many absurdities.
For example, no matter how prosperous the American East Coast was, it could not support three megacities. Having Gotham and Metropolis alone was already unbelievable enough; there simply was no room for another.
Nor had anyone replaced anyone else. Every difference between the two Earths had been preserved, and the people, buildings, and all kinds of social relationships had been moved over exactly as they were.
That created a problem: Gotham and Metropolis could not accommodate the nearly ten million extra residents of another megacity. But that was actually the easiest part to solve. They only needed to make the Earth a little bigger.
In fact, Lucifer, as the Battleworld Administrator, had experience in that regard. New Earth of the Battle Realm was an enlarged version of Earth, so in a sense, this new Earth-1 was a beta test version of Battleworld Earth.
After the expansion, New York's original buildings could, with a little planning, be fitted intact into Metropolis and Gotham. The population was the same.
In other words, New York now lay interwoven between Metropolis and Gotham. Yet it did not look strange, because Metropolis and Gotham themselves had been designed after New York by day and night. Though the details of each building differed, their styles blended perfectly.
The city most changed by the fusion was Gotham. Prosperous Manhattan had occupied only a small part of New York, which merely gave Metropolis an additional commercial center. The other three boroughs had all fallen into Gotham, while the remaining island was closer to Gotham as well. Calling it a fusion of New York and Gotham would not have been an exaggeration.
So after such an earth-shattering