Do you know how you and the publisher are compensated in this situation? I'm assuming there is some sort of royalty stream coming back to you? (I'm not asking for details, just generalities).
I'll answer since they didn't. Kindle Select is direct publishing only, so they don't have another publisher.
They get paid based on number of their reads (that's anyone who reads >10% of their book) as a proportion of number of total reads across the library, calculated against a money pool that Amazon determines month over month and tunes to keep the program attractive.
