Hmm, but what mechanism would be responsible for a 'body-swap' within the Animorphs universe, I wonder? It sounds like it would almost have to be some odd glitch from the morphing technology itself.
Wait, wait, I've got it. So their minds go off to z-space every time they morph, yet stay connected to their morphed bodies by mystical Andalite voodoo that primitive humans do not understand, correct? Well, perhaps the Yeerks can invent something to sever the connection, in the hopes that it will insta-kill any morphed Andalites in the area. But, then (Ax can explain this part with more bigger words) the disconnected minds instead graft onto the nearest available mindless morphed bodies.
Badda bing, instant shenanigans. Yep, that one could definitely be an Ax book. So he can narrate all condescendingly and superior-like. Although, it might also make some sense to be for Tobias, because he would be like "OMG this is what it was like to be human, and have a family and a bed and human-food WTF am I doing still being a hawk ANGST ANGST ANGST"
Of course, you have to consider that the Animorphs have the innate advantage over characters from other series that they can just morph one another to correct the effect (for two hours at a time). Still, though, it would be a problem and they'd all want it fixed. Jake and whoever wound up as "Jake" in particular, since the real Jake could not afford to be demorphing every two hours with Tom around.
As for important stuff that then gets forgotten in later books . . . come on, that's half the series, you guys. Other than major developments that are obviously still relevant after the fact, is there anything that
ever happens that the Animorphs actually remember after the book where it happened? So, yeah, short of huge stuff, we could basically insert any book anywhere and not change anything.
The Replacement: The only Cinnabon within walking Distance has gone out of business. Ax must find a replacement for his favorite food.
This could very well be the most deadly-serious mission the Animorphs have ever undertaken . . .