You have all of those?!?
You say that "The parody ONLY works if you have read (or know) the original." Having received a copy of one of the Barry Trotter books as a birthday present a few years back, and having flicked through most of the others you mention, I can confirm that the parody doesn't work at all, certainly not in the case of any of these dull, cheap, obvious, unfunny, utterly pointless works.
If those books are illegal then I would say "good", and call for the full force of the law to be unleashed immediately, to stamp out this drivel forthwith.