The four shadows at the "gathering" probably ties into all of this somehow.
Since I watched Little Buddha
recently, I'll suggest an alternative to (or expansion upon) Salty's "two souls per child" thing. So how about:
At 2I, Adam was fractured in every way conceivable. Body, soul, you name it. Four new energy beings were generated, featuring four shards of Adam's soul, each acting as some "aspect" of the original. Together they would have brought on the end of the world, but stuff happened. Adam exploded into blood everywhere. The four Adam-lettes reverted into physical beings, somehow separated from the soul shards in the process, and were thrown all over the place.
"The children of preordained fate" have the Adam soul-shards possibly salvaged on purpose into volunteer human mothers following 2I. As a result of gestation, the shards have been "filled in" with human 'spirit', but they're still Adam at the core.
This provides some sort of explanation for, among other things, the much-added emphasis on the ATF emanating from the entry plug and not just the Eva's core. It can also explain obnoxious things like why pilots seem so terribly swappable; they're all engaging in the same sort of hax Kaworu was doing in the original.
Kaworu would possess the "central" piece of Adam, as mentioned.
Also, does Kaji's lolwtf line make any more sense within a "four Adams = impact" framework?
Kaji wrote:Triggering Unit-01's awakening before the rest are present... Commander Ikari, Seele won't keep quiet about this.
And I don't know what's going on anymore, so I'll stop.