Adding books into series

[Victoria]

Hi,
I have a prequel and the first book that I've tried to add together into series, but it doesn't seem to put them together.
Could you help with adding them into series, please.

https://www.goodreads.com/book/show/5...
https://www.goodreads.com/book/show/6...

[Sally]

Hello!

I made a series and added the first book, see here: https://www.goodreads.com/series/3525...
However, I'm reading in the description of the prequel that the story is only available via newsletter? Because if so, it doesn't meet the criteria to be included in the database in the first place.