First of all, tell me a little about your series and introduce us to the sequel(s).
The Finding Humanity series is a sci-fi hopepunk adventure with paranormal, mystical, and romance threads. In a future ice age, Bleu’s expedition team emerges from their subterranean haven to discover humans are no longer the dominant life form on Earth. Bleu is one of the five POV that get caught up in the resulting chaos. The series name has a double meaning. It comes from the human survivors both searching for other survivors, and also being challenged by the star beings who now control the Surface to change their ways and give up violence and destruction of the environment or face the consequences. The series deals with whether or not humans as a whole can change and survive without violence in an often violent world.
The first book, The Calling, features five POVs (three humans and two star beings) and the near war that occurs when these two civilizations meet. 
The second book, The Chasm, continues the same five POVs, but now the humans become reluctant allies with the star beings and together search for more human survivors. Instead, they discover a fierce, new threat that sheds doubt on their new allies.
The third book, The Ruined, is still in edits. This book adds two new POV, the new threat (the Ruined) is expanded on, and the full danger to the planet and humanity is revealed.
There are six main books planned in the series, and several side stories that take place between books. Currently, the only sequels published are The Chasm, and a side story, The Cords That Bind, that takes place between the first two books. The Cords That Bind features the POV of Eka, one of the star being teens, as he tries to uncover the strange energetic connection he has with another one of the team members (his LI, Rana), and how it relates to a past unsolved death. 

You can get copies of those books from Amazon.

Do you find that most of your readers continue to read the whole series? Why do you think that is?  
I find most of the readers have gone on to read The Chasm because they’re invested in the characters. They’ve also contacted me asking me to hurry up with The Ruined, so I think I have pretty good interest in the series. But several readers have told me they didn’t know The Cords That Bind existed, because of the way online retailers often don’t list it as part of the series.

How difficult is it to add new characters in a sequel into already established relationships? 
Because the expedition team is seeking other survivors, it's not hard to add new characters. My new characters pretty much just show up and introduce themselves to me, telling me their story. It's easy to add them in, though my established characters don’t always like the new ones, lol. 

Is it difficult to continue with worldbuilding for a world you have already built in book 1?  Do you find it easier to switch locations for the sequel and start again with worldbuilding? 
I started working with these characters and this world thirteen years ago, so at this point I know it quite well. I know way more facts about this world and its species and cultures than I’ll ever be able to fit into the books. It started with several locations (below ground in the human haven and the glacial Surface above), and I knew this story would eventually be grand in the scale of including the entire planet by the end. I can’t wait to share some of the upcoming locations.

Have you ever been stymied by a worldbuilding or plot detail from book 1 that is very inconvenient to deal with or write your way around in subsequent books?
Not so far, lol. Compared to other books I’ve written, this series has been a very unusual experience. These characters are telling me their story, and I’m pretty much just a scribe, translating their lives into novel form. There were things that happened in the first book that I knew had to be included, but didn’t fully understand the importance of until now, as I write the third book. I never consciously planned those original details and was reluctant to publish them, because I was afraid they might stymie me later. But I trust this unusual writing process I’ve worked out with these characters. As they tell me more, I realize now (writing book 3) why those hints had to be included in the first book, and won’t fully play out until the end. It's a very strange experience.

Would you say your craft has improved with the subsequent books?
The first book took me ten years, and I rewrote it endless times trying to gain the skills to tell the story the way I wanted it to be told. I now find it easier and much faster to write, and my craft has definitely improved, but I’m still very happy with the way the first one came out.  

Do you have all the timeline planned for the full series?
I know there will be six books, and I know how the series ends. I have the basic adventure of each book summarized in my head in a few sentences, and I know who lives, dies, and who ends up where and with whom. But I don’t know any details of how my characters accomplish what they will accomplish until I write each scene. 

Do you have any marketing tips for sequels?
I’m not in any way a marketing guru. I find staying active on social media and making jokes about my characters and giving non-spoiler writing snippets keeps the series active in readers’ minds. I also give a small amount of information about the next book at the back of each preceding book, and I’m trying to write and edit as time efficiently as possible to keep the series moving. That’s all I’ve figured out marketing-wise.