Convert EPUB to BKK

It doesn't seem very likely that you can directly create BookBuddi ebooks out of EPUB publications, which is what epub to bkk conversion would be.

Nonetheless BookBuddi can be most likely used create its own book files (.bkk) from textual sources, so export the EPUB to RTF or maybe EPUB and HTML and import it to BookBuddi.

Simply put, it is impossible to convert EPUB to BKK directly.
Thus, there is no so-called epub to bkk converter or a free online .epub to .bkk converter to be found.