[BobC]

I used to use fb2 for all my ereading so have a bit of experience with the problem you have. Ultimately I think it comes from the fact that with fb2 the entire book is a single contiguous file so the referring page and the footnotes are in memory at the same time. This means that the design of a reader that will display both items simultaneously is more practical than if they are in separate files.

I found that the best way to create an ebook with footnotes in fb2 format which displayed in the way you want, which is the way Word-processors like MS Word and LibreOffice Writer display footnotes was to use LibreOffice and the OOOFBTOOLS add-in which has a number of tools for working with footnotes. It will also output the file in fb2 format.

The real issue is, however, will the final fb2 file be too large for your reader to handle sensibly - I've built a few files that are o.k. but the reader won't handle or get slower and slower as you get further into the book.

As an aside I note that the calibre viewer using epub will display footnotes (which are in the same internal file as the referring file) in the way you would like but if they are endnotes (contained in a separate file) you need to follow the link to display them. This demonstrates the problem.

So If I were determined to do exactly what you want I would start by converting the EPUB to a format that LibreOffice could open (e.g. DOCX) and then sanitize the footnotes in there until they displayed correctly in LO (i.e. at the page bottom). Then use the OOOFBTOOLS exporter to write out the FB2.

OOOFBTOOLS has the capability of recognizing different footnote/endnote reference styles in plain text documents and batch converting them to "proper" foot/endnotes so the task may not be too onerous once you have mastered the various steps needed. These will be different if, for instance footnotes are sequentially numbered throughout to book or on a per-chapter basis.

I have used these tools in the past on books with hundreds of footnotes and I still use the footnote tools even when I intend to create an EPUB using a different export filter from LO.

IIRC the fb2 output from Calibre did have a few issues associated with footnote (and perhaps other) links but as a little-used format that's not surprising.


BobC