Teen Power Inc.

Teen Power Inc., now known as Raven Hill Mysteries is a series of books created by notable Australian author Emily Rodda, even though many of the books are actually penned by other authors who receive credit on the inside title page. The series, originally published in the mid-1990s is being reprinted under the name "Raven Hill Mysteries". As of 2006 the first six titles have been reissued.
Premise.
The series revolves around six teenagers who have set up a part-time job agency, Teen Power Inc. (changed to Help-for-Hire in the republished editions) to work for cash before and after school. Usually, their jobs end up getting them into trouble and each book in the series generally revolves around one main mystery for the gang to go through; with the narrator being the crime-solver. The squad consists of: Richelle Brinkley, Sunny Chan, Liz Free, Nick Kontellis, Tom Moysten and Elmo Zimmer.
Structure.
Each novel in the series is narrated by a different person. For the first fourteen books, the narration followed the cycle order of Liz-Tom-Richelle-Elmo-Sunny-Nick. However, after book 14 (Tom), book 15 was narrated by Sunny instead of Richelle. The series reverted to the original order for the fourth cycle (books 19-24) but then scrambled again for the fifth and last cycle (books 25-30), with Richelle starting the narration instead of Liz. However, each cycle of six books without exception has one contribution from every member of the Teen Power Inc group.
The Raven Hill Mysteries reprint.
The Teen Power Inc books were relaunched in the US in 2006 under the name "Raven Hill Mysteries". In the reprints, the name of the job agency is changed to "Help-for-hire" and certain book titles were also changed (such as "St Elmo's Fire" becoming "Deep Secrets"). Further, the order of the reprints has been scrambled, causing major continuity problems given that the final book in the original series ("Dead End") which dealt with a criminal from Teen Power's past coming back to seek revenge on the gang which put him in jail, has been published sixth in the new series and prior to the book which first introduced this criminal.