Trouble adding 3rd book to series

[T.R.]

I have two of the books in my series, The Fearless Trilogy, but can not add my third book to the same series. I've read all the posts online, gotten to the series page which shows my two books but there is not a button called 'Add to Series' anywhere.

My series is 'Fearless', the two books already there are Death Catch and Drone Catch. My third book is SEAL Catch.

Can someone assist me?

Many thanks, Tracy

[☕ Lachgas ♿]

Added it.
Only librarians can do that, so you did nothing wrong