more than 6 devices can synch to 1 account
but only 6 devices can concurently access a book.
so for us the math is
24 physical books
4 electronic books synched to 4 sets of 6 kindles
it does work and Amazon said it was OK
its my understanding the this used to be the case on nooks, but no longer (not sure why).
How was this person able to get a class set of books for her Kindles for $28?