How do I find and move non-purchased books from iBooks to Kobo?

Received many books from authors through book funnel. Opened in iBooks. I’d like to move to my kobo. The only books that show up in iCloud or files are the purchases direct from iBooks. The only way I can find the files is with searchlight and when I try to move them they are epub files but each chapter is a separate file. This really makes me not want to use iBooks. Any ideas? Thank you

[Re-Titled by Moderator]