...whether I'm missing something, or being too literal about a story that's not intended to be, or what.

But one of the descriptions says that they only add someone like Nyx about once a century. And there's nothing said about those who were there before who have been replaced; none of the originals from the 14th century seem to be present, and few of those since then. The implication seems to be that they're immortal, so unless they have duels against possible successors -- which wasn't true in Nyx's case -- I can't see what's happening to them.

And obviously there's something that Ethan had that differentiated him from folks like the one who invaded the circle a week later. I initially thought the "If true, then how many sisters already dance beyond our counting?" referred to the ones who were replaced by successors at the rate of about one per century, but I guess it makes more sense for it to mean these others, since they're apparently coming just weeks apart rather than centuries.

Eric