I would love to know the answer to that question. I have a nook and wanted to download a book but it wasn"t available on B&N sight or library. Found it at Sony store so after reading everything and coming to the conclusion that purchases would be recognized by ADE I bought the book. I can read it on Sony's Reader library off my computer but it is not showing on ADE sight. Talked to tech. support and they were clueless as to what I was getting at. If you read the sights it claims that ADE will check with Reader to exchange content.
if anyone knows how to get Sony Reader purchased content to show on ADE I would love to hear from you. ADE has a puchased content on bookshelf but how the heck do you get the books to show there!
I was able to get content from Reader to nook. I was fooling around so not quite sure how I did it but hopefully it is enough information for you to get lucky too. From Reader library I imported books to document file. Then I went into ADE library and clicked add to library-looked for documents from Reader then transferred. Files showed up in bookshelf purchase. Once there I connected my nook and transferred. Content shows up in documents but reads like a purchased item. Library downloads are limited in font and text size and I find the content off center. hope this helps! Good Luck!