Migrants of Multiple Earths Thesis: Part 1

A seemingly throwaway line at the conclusion of a confrontation between the Freedom Fighters from Earth-Two, while battling their world's Baron Blitzkrieg on the hero-less Earth-X, was that the cosmic balance was jeopardized due to the All-Stars' presence on a world not their own. 

The three who remained behind on Earth-X were Uncle Sam, Black Condor and the Ray; after three Nazi troopers returned with the Baron to Earth-Two to serve him on his home-world. 

Months earlier, Sam had brought other heroes to Earth-X, all of whom (save for Hourman and Sam) remained on this world before their premature deaths protecting that world’s Pearl Harbor.

According to the law of conservation of mass, also known as the principle of mass/matter conservation, is that the mass of a closed system will remain constant over time. The mass of an isolated system cannot be changed as a result of processes acting inside the system. A similar statement is that mass cannot be created/destroyed, although it may be rearranged in space, and changed into different types of particles.

So the mass of these metahumans removed from one closed system, or universe, and transferred into another. How did the multiverse compensate for this unauthorized transfer? Well another incursion happened shortly thereafter when several Nazi troops followed Midnight and Doll Man back from the Nazi's Earth-X to the heroes' Earth-Two:

In the third panel, if you squint you can make out eight soldiers on the opposite rooftop from Midnight, and two falling presumably to a life-ending landing. That's ten, so five of these would cancel out the five late heroes Red Torpedo, Magno, Miss America, Neon the Unknown and the Invisible Hood. The remaining Nazi troopers correlated with Uncle Sam and Hourman (whom Red Bee later traded places with on Earth-X when Hourman returned to Earth-Two), as well as Doll Man, Midnight and Baron Blitzkrieg who simultaneously traveled to Earth-X at the same time as the fatal five freedom fighters.

So the total number of Nazi soldiers and Fighters who permanently moved Earth balanced out, thus compensating for the transfer of mass. 

During this initial encounter between two parallel Earths, this formative Freedom Fighters departed Earth-Two to protect the Pearl Harbor of Earth-X from a devastating attack, with five of the seven perishing when a kamikaze pilot took their lives (note: Uncle Sam and Hourman, due to their invulnerability, survived this encounter). Meanwhile, Doll Man and Midnight followed Uncle Sam through his portal to Earth-X, and then retreated back to Earth-Two a couple months later with the aforementioned ten Earth-X Nazi troops who followed them.

While most of these Nazis soon perished, five of their number became Baron Blitzkrieg’s henchmen the Human Bombs, which were quickly dispatched by Wonder Woman. Five foes of freedom…five fighters of freedom, removed from the cosmic equation in the 1st Freedom Fighters and Nazi Human Bombs.