I like the idea of having this app to limit our kids' usage, especially during school days. But we have a serious issue. We cannot add most of the books to the Free Time menu. We have only purchased two books from Amazon, the rest have been purchased from other sites. The two books we did purchase from Amazon can be added to the Free Time list. So I am assuming that only Amazon books are valid with this app. So a couple of questions:

1) Is there a way around this issue (need to be able to add any book to Free Time)?

2) If there is no 'backdoor' method to question one, is there another similar app available?