A I am not American and so have not followed this story, in fact I knew nothing about it until reading this article. The first thing that strikes me as “odd” is the use of Wikipedia (no fault or slur intended on a fantastic organisation)as a source of information/history/reference. As a writer I love Wikipedia which is packed full of interesting information, I return to it often both as a source and a starting point. Yet everyone is aware that not all on Wikipedia is always correct and so you take the information received and then research it yourself before writing the next word in your manuscript. I would normally at that point cast off the allegations as silly but there is far too much coherence for that to be the case. I do expect that Jill Bialosky is guilty of Plagiarism but suspect that she is a great deal more guilty of being lazy and wishing to earn money from her name rather than producing the work required.
I feel sure that I could write a book in 24 hours if i simply cribbed it from elsewhere. I suspect that Jill just needed a little cash injection.