I tried to figure out how to do this, but I think the writer/publisher has to. Semi-Twisted is not currently listed as Harper Hall Investigations, #3 on Goodreads, so it's not showing up as part of the series. Thought you should know. Also, book 4 that's supposed to come out this year isn't listed at all. Goodreads reminds people when a book on their list is published, which could help you some. Maybe you could fix?