Per evitare le righe orfane ho aggiunto \nobreak.
`% ridefinisco la macro 'author'
\makeatletter
\renewbibmacro*{author}{%
\ifthenelse{\ifuseauthor\AND\NOT\ifnameundef{author}}
{\ifthenelse{\iffieldequals{fullhash}{\bbx@lasthash}\AND
\NOT\iffirstonpage}
{}
{\savefield{fullhash}{\bbx@lasthash}%
\par
\hskip-4\bibhang
\printnames{author}
\par\nobreak
\vskip1em plus 2pt minus 2pt
\hskip-4\bibhang
\iffieldundef{authortype}
{}
{\setunit{\addcomma\space}}}%
\iffieldundef{authortype}
{}
{\usebibmacro{authorstrg}%
\setunit{\addspace}}}%
{\global\undef\bbx@lasthash
\usebibmacro{labeltitle}%
\setunit*{\addspace}
}%
\usebibmacro{year+labelyear}}
% ridefinisco la macro 'editor'
\renewbibmacro*{editor}{%
\ifthenelse{\ifuseeditor\AND\NOT\ifnameundef{editor}}
{\ifthenelse{\iffieldequals{fullhash}{\bbx@lasthash}\AND
\NOT\iffirstonpage}
{}
{\savefield{fullhash}{\bbx@lasthash}%
\par
\vskip1em plus 2pt minus 2pt
\hskip-4\bibhang
\printnames{editor}
\par\nobreak
\vskip1em plus 2pt minus 2pt
\hskip-4\bibhang
}%
\clearname{editor}%
}%
{\global\undef\bbx@lasthash
\usebibmacro{labeltitle}%
\setunit*{\addspace}}%
\usebibmacro{edyear+labelyear}}`
Alcune tipologie di voce bibliografica sono ancora sbagliate (manual, online, set, per esempio), ma non dovrebbe essere difficile sistemarle.
Ciao
Ivan