I know that this is a fiction series, and all the happenings probably wouldn't have happened in real life anyway, but I'd like to discuss about how the BluexOak kit exchange was completely nonsensical.
First of all, Bluefur named her three kits Mistykit, Stonekit, and Mosskit. Coincidently, two kits named Mistykit and Stonekit show up in RiverClan shortly after they are eaten by foxes. The kits were also IDENTICAL to the eaten kits. Did ANY cat at all wonder why?
Second of all, the kits were old enough to talk and play at the time Bluefur passed them on. When they got to RiverClan, did they pine for her at all? Did any cat wonder why they kept asking for Bluefur? Sure, they were half dead, but I don't think their memory would have been drained by the time they recovered. Bluefur was their mother. It would make sense for them to wonder where she was. If they told RiverClan that, the secret would be already out.
You can't just pass kits from one clan to another and expect no one to notice. Some ThunderClan cat, especially their "father" Thrushpelt or Featherwhisker would definitely have recognized the two RiverClan apprentices at their first gathering. When a she-cat has kits, every cat wants to see. There probably wasn't a single cat who hadn't visited Bluefur in the nursery.
I guess a few complication were overlooked?
Again, fiction series, unrealistic in the first place, but still. Kit exchange could not possibly have worked.