When turning headlines into plain lists ~(org-ctrl-c-minus)~, I think 
footnotes should be moved to the bottom of the main headline.

Example; Original headlines:

* Main headline
** Headline 1
bbbbbbbb [fn:1]

[fn:1] cccccccccccccccc
* Headline 2


~C-c -~ turns that into a list where footnotes definitions can't be 
found. It gives, for example, problems when exporting or when more 
footnotes are added:

* Main headline
- Headline 1
   bbbbbbbb [fn:1]

   [fn:1] cccccccccccccccc
- Headline 2


The desired outcome, could be something like this:

* Main headline
- Headline 1
   bbbbbbbb [fn:1]
- Headline 2
[fn:1] cccccccccccccccc