So, in the "two Nexi" model, Cyan's Nexus would keep the hoods, the invites, and the link to Cyan ages in D'ni, which would (without a visible distinction) extended by fan-ages in D'ni. The Writer's Nexus would contain all the other fan-ages. In both cases, fan-ages could be either permanently visible or collected as a bonus. The Nexus stations registering non-D'ni-fan-ages (those connected to the Writer's Nexus) would be similar to the other ones, but with a clear distinction. Maybe I can add the Writer's Nexus to the existing Nexus book (though that'd be a bad hack, since the book only appears if you actually got a Nexus instance... but well, the whole Shelf is a really bad hack), or it would need another easy way to be reached from Relto.
In the "one Nexus" model, the fan-created Nexus would get the same sequence prefix and age name as the original one. It would then replace it, and you would end up in there whenever any age links to Nexus. Slightly less confusion about two Nexi, but concerns (due to removing a Cyan age), maybe IC trouble, and a more crowded interface (as the hood, invite, and large age set functionality would have to be present in just one GUI). Oh, and more coding work to clone the original Nexus' behaviour
