part of the premise of the books is that the characters do not share their last names in them because if a controller was to get their hands on them (I guess the books exist within the universe of the books? must investigate furtehr) they would be able to find them and kill them
but another part of the premise is that since they acquired their morphing abilities from andalite technology, the yeerks always assumed that they were stranded andalite warriors conducting raids.
but the same books that refuse to reveal their last names (until late in the series) DO reveal that they are humans, which is also potentially detrimental to their cause. can these two concepts be reconciled? help
The whole book is a plothole
An equally large part of the premise is that the public needs to be alerted that they're in danger. The kids probably thought that letting people know about the Yeerks was more important than keeping up the Andalite ruse.