I have now, at long last, finished "Original Sin" by David R George III, published September 26, 2017.
Part of this was that other hobbies pulled me away (I played a lot of Hades II in bed instead of reading), and part of it was that the middle of this book really felt slow. We have two narratives, switching back and forth between them, which I've disliked before, and both stories seem to lull at the same time. The payoff for it at least is good, as the conclusion of the kidnapping of Rebecca story (which admittedly we know will conclude favorably because she is not dead) would drop the stakes a bit on the "kidnapping of all the children aboard the Robinson" storyline. The reveal here is that Rebecca has the ability to turn back time if in enough distress. This seems to work by moving her consciousness back in time in her body, but then unleashing a large amount of energy which both times alerts the searchers and allows her rescue. I was a little unsure of how the time travel worked at first, but I think that's how it does.
The main antagonist in the present-day storyline is an interesting sci-fi species known as the Glant, which each have a unique body plan. They kidnap the children, as is eventually revealed, because they engineer their next generation but need malleable minds to transfer into them. They attempt to negotiate with the starfleet crew but essentially consider the humanoids as inferior and will not give the children back because they want them for their next generation. It's a bit unclear as to how the mind transfer works, since Rebecca is transferred but keeps all her memories (maybe it wasn't complete?), and I would imagine their society would have a lot of issues with children blaming the species for abducting them. It's horrifying, to be sure, and is a good reason for why starfleet cannot negotiate with them.
I'd say the sagging middle, plus the lack of distinct focus on any character, made this one rank lower than the other post-destiny/fall DS9 books. I think there are some interesting concepts here, but it could have been trimmed or combined with others.
At this point I assume there won't be any more of Rebecca Jae Sisko. I was interested to see what more they would do, but perhaps that's a stone best left unturned. Next up for me, I think I'll try the section 31 stories before a treat of Enigma Tales.