Sorting scheme for specific entry-types in biblatex

Question

I'm using nty sorting scheme, but I need @proceedings and @inproceedings entries to be sorted by eventtitle before booktitle in @inproceedings and before title in @proceedings. The order should be author→title→eventtitle→number→booktitle→date/year

^{(This is because I'll have to put eventtitles before booktitles in @[in]proceedings entries)}

I managed to achieve something with \DeclareSortingScheme, but it interferes with the sorting of other entry types, e.g. anonymous articles.

A non working MWE

\documentclass{article}
\begin{filecontents}{\jobname.bib}
  @proceedings{A,
    eventtitle = {Symposium of Given Field},
    number = {2},
    venue = {London},
    title = {Annals of the Second Symposium of Given Field},
    date = {2000},
    location = {London},
    publisher = {Publisher},
  }
  @proceedings{B,
    eventtitle = {Congress of Another Field},
    number = {10},
    venue = {Paris},
    title = {Proceeding of the 10\textsuperscript{th} Congress of Another Field},
    date = {2013},
  }
  @article{C,
    title = {The anonymous article},
    journal = {Journal},
    date = {2013-09-10},
  }
\end{filecontents}
\usepackage[style=authortitle,sorting=nyt,backend=biber]{biblatex}
\addbibresource{\jobname.bib}
\DeclareSortingScheme{mysort}{
  \sort{
    \field{presort}
  }
  \sort[final]{
    \field{sortkey}
  }
  \sort{
    \field{sortname}
    \field{author}
    \field{editor}
    \field{translator}
    % \field{sorttitle}
    % \field{title}
  }
  \sort{
    \field{eventtitle}
    \field{number}
  }
  \sort{
    \field{sorttitle}
    \field{title}
  }
  \sort{
    \field{sortyear}
    \field{year}
  }
  \sort{
    \field[padside=left,padwidth=4,padchar=0]{volume}
    \literal{0000}
  }
}
\begin{document}
\nocite{*}
\printbibliography[sorting=nyt,title={\texttt{nyt}-sorted Bibliography}]
\printbibliography[sorting=mysort,title={\texttt{mysort}-sorted Bibliography}]
\end{document}

Answer 1

I'm not sure if this is what you want to achieve:

MWE (I just changed a little your custom sorting scheme)

\documentclass{article}
\begin{filecontents}{\jobname.bib}
  @proceedings{A,
    eventtitle = {Symposium of Given Field},
    number = {2},
    venue = {London},
    title = {Annals of the Second Symposium of Given Field},
    date = {2000},
    location = {London},
    publisher = {Publisher},
  }
  @proceedings{B,
    eventtitle = {Congress of Another Field},
    number = {10},
    venue = {Paris},
    title = {Proceeding of the 10\textsuperscript{th} Congress of Another Field},
    date = {2013},
  }
  @article{C,
    title = {The anonymous article},
    journal = {Journal},
    date = {2013-09-10},
  }
\end{filecontents}
\usepackage[style=authortitle,sorting=nyt,backend=biber]{biblatex}
\addbibresource{\jobname.bib}
\DeclareSortingScheme{mysort}{
  \sort{
    \field{presort}
  }
  \sort[final]{
    \field{sortkey}
  }
  \sort{
    \field{sortname}
    \field{author}
    \field{editor}
    \field{translator}
    \field{eventtitle}
    \field{number}
    \field{sorttitle}
    \field{title}
  }
  \sort{
    \field{sortyear}
    \field{year}
  }
  \sort{
    \field{sorttitle}
    \field{title}
  }
  \sort{
    \field[padside=left,padwidth=4,padchar=0]{volume}
    \literal{0000}
  }
}
\begin{document}
\nocite{*}
\printbibliography[sorting=nyt,title={\texttt{nyt}-sorted Bibliography}]
\printbibliography[sorting=mysort,title={\texttt{mysort}-sorted Bibliography}]
\end{document}