Shannon Messenger had written 8 books and an extra book (8.5). Her contract is only for 9 books but she may renew it if she cannot finish the series in the upcoming ninth book. The ninth book is said to be coming out in fall of 2021. Does that help you?
I'm pretty sure she is going to write 10 books in the series, but i might be wrong
Keeper of the lost cities (nicknamed “Keeper” by the fandom), Exlie, Everblaze, Neverseen, Lodestar, Nightfall, Flashback, Legacy, Unlocked (which is technically an extension book and not counted as part of the series), and the unknown book nine, which will come out this October.
The series guide
The duration of Brother's Keeper - TV series - is 1320.0 seconds.
Brother's Keeper - TV series - ended on 1999-05-14.
Brother's Keeper - TV series - was created on 1998-09-25.
The Giver is the first book in the series, followed by Gathering Blue, Messenger, and Son.
My Brother's Keeper A Drama Series - 2006 1-1 was released on: USA: 2 February 2006
My Brother's Keeper A Drama Series - 2006 1-2 was released on: USA: 9 February 2006
My Brother's Keeper A Drama Series - 2006 1-3 was released on: USA: 16 February 2006
My Brother's Keeper A Drama Series - 2006 1-4 was released on: USA: 26 February 2006
My Brother's Keeper A Drama Series - 2006 2-2 was released on: USA: 16 June 2008
My Brother's Keeper A Drama Series - 2006 2-4 was released on: USA: 16 July 2008