Found how to do it. Can't delete this thread, unfortunately.
Can somebody help me to find where is the problem?
When converting to fb2 format, I have set up my own format for author name and book gender. So that when I convert EPUB into FB2, it looks like:
Code:
<genre>sf</genre>
<author><first-name></first-name><last-name>name of the author</last-name><home-page>http://archiveofourown.org/users/authorNickname</home-page></author>
Then I use Save to disk, to more easily find book to copy. And in resulting books that part looks like that:
Code:
<author><nickname>authorNickname</nickname></author>
<genre>The Lord of the Rings - All Media Types</genre>
<genre>FanFiction</genre>
And the previously converted book still looks as I want it too.