Biblatex always show a specific author

Question

I am looking for a way to always list one specific author in references with many authors, when the number of authors to show is limited and abbreviated by et al.

For example

These are the relevant papers:
\fullcite{paper1}
\fullcite{paper2}

should result in

These are the relevant papers:
Author, A., ..., Alwaysthisauthor, X., ..., et al. 
Buthor, B., ..., Alwaysthisauthor, X., ..., et al.

As requested a minimal example is below:

\documentclass{article}

\usepackage{filecontents}
\usepackage[backend=biber,natbib]{biblatex}

\begin{filecontents}{\jobname.bib}
  @INPROCEEDINGS{2001AIPC..569..163C,
   author = {{Cheshkov}, S. and {Tajima}, T. and {Chiu}, C. and {Breitling}, F. },
    title = "{Emittance control in Laser Wakefield Accelerator}",
booktitle = {American Institute of Physics Conference Series},
     year = 2001,
   volume = 569,
    month = may,
    pages = {163-176},
}

@ARTICLE{2001RScI...72.1339B,
   author = {{Breitling}, F. and {Weigel}, R.~S. and {Downer}, M.~C. and
    {Tajima}, T.},
    title = "{Laser pointing stabilization and control in the 
        submicroradian regime with neural networks}",
  journal = {Review of Scientific Instruments},
     year = 2001,
    month = feb,
   volume = 72,
    pages = {1339-1342},
}
\end{filecontents}

\addbibresource{\jobname.bib}

\begin{document}
\nocite{*}
\printbibliography
\end{document}

Results in

References

1. F. Breitling et al. “Laser pointing stabilization and control in the submicro-radian regime with neural networks”. In: Review of Scientific Instruments 72 (Feb. 2001), pp. 1339–1342.

2. S. Cheshkov et al. “Emittance control in Laser Wakefield Accelerator”. In: American Institute of Physics Conference Series. Vol. 569. May 2001, pp. 163–176.

But I need the name Breitling to always appear explicitly also if the author list is truncated with et al.

Answer 1

The following is adapted for biblatex >= 3.3 from my answer to Excluding one certain author from [et al.].

In order to make this solution work you will need the hash of your name, see Highlight an author in bibliography using biblatex allowing bibliography style to format it for details on how to retrieve the hash for specific names from the .bbl file.

If you wrap your name into braces, the hash for F. {Breitling}/{Breitling}, F. is 3f71afbcde39f096d711d45fa2c17bc7.

\documentclass[british]{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{babel}
\usepackage{csquotes}
\usepackage[style=authoryear, backend=biber, maxnames=999]{biblatex}

\begin{filecontents*}{\jobname.bib}
@INPROCEEDINGS{cheshkov,
   author = {{Cheshkov}, S. and {Tajima}, T. and {Chiu}, C. and {Breitling}, F. },
    title = "{Emittance control in Laser Wakefield Accelerator}",
booktitle = {American Institute of Physics Conference Series},
     year = 2001,
   volume = 569,
    month = may,
    pages = {163-176},
}
@ARTICLE{breitling,
   author = {{Breitling}, F. and {Weigel}, R.~S. and {Downer}, M.~C. and
    {Tajima}, T.},
    title = "{Laser pointing stabilization and control in the 
        submicroradian regime with neural networks}",
  journal = {Review of Scientific Instruments},
     year = 2001,
    month = feb,
   volume = 72,
    pages = {1339-1342},
}
\end{filecontents*}
\addbibresource{\jobname.bib}
\addbibresource{biblatex-examples.bib}

\newcounter{namesnotimportant}
\newtoggle{ellipsis}

\makeatletter
\newbibmacro*{name:etal:delim}[1]{%
  \ifnumgreater{\value{listcount}}{\value{liststart}}
    {\ifboolexpr{
       test {\ifnumless{\value{listcount}}{\value{liststop}}}
       or
       test \ifmorenames
       or test {\ifnumcomp{\value{namesnotimportant}}{>}{0}}
     }
       {\printdelim{multinamedelim}}
       {\lbx@finalnamedelim{#1}}}
    {}}
\makeatother

\DeclareNameFormat{given-family-etal}{%
  \letbibmacro{name:delim}{name:etal:delim}%
  \ifnumcomp{\value{listcount}}{=}{1}
    {\setcounter{namesnotimportant}{0}%
     \global\toggletrue{ellipsis}}
    {}%
  \ifboolexpr{test {\ifnumcomp{\value{listcount}}{=}{1}}
              or test {\ifnumcomp{\value{listtotal}}{=}{2}}}
    {\ifgiveninits
      {\usebibmacro{name:given-family}
         {\namepartfamily}
         {\namepartgiveni}
         {\namepartprefix}
         {\namepartsuffix}}
      {\usebibmacro{name:given-family}
         {\namepartfamily}
         {\namepartgiven}
         {\namepartprefix}
         {\namepartsuffix}}}%
    {\iffieldequalstr{hash}{3f71afbcde39f096d711d45fa2c17bc7}%% <----- put the correct hash here
      {\global\toggletrue{ellipsis}%
       \ifgiveninits
        {\usebibmacro{name:given-family}
           {\namepartfamily}
           {\namepartgiveni}
           {\namepartprefix}
           {\namepartsuffix}}
        {\usebibmacro{name:given-family}
           {\namepartfamily}
           {\namepartgiven}
           {\namepartprefix}
           {\namepartsuffix}}}%
      {\stepcounter{namesnotimportant}%
       \iftoggle{ellipsis}
         {\addcomma\space\textellipsis\global\togglefalse{ellipsis}\isdot}
         {}}}%
  \ifboolexpr{
    test {\ifnumequal{\value{listcount}}{\value{liststop}}}
    and
    (test \ifmorenames
     or test {\ifnumcomp{\value{namesnotimportant}}{>}{0}})
  }
    {\andothersdelim\bibstring{andothers}}
    {}}

\DeclareNameAlias{sortname}{given-family-etal}
\DeclareNameAlias{author}{given-family-etal}
\DeclareNameAlias{editor}{given-family-etal}
\DeclareNameAlias{translator}{given-family-etal}

\begin{document}
\nocite{cheshkov,breitling,aksin,worman,nussbaum,geer,sigfridsson}
\printbibliography
\end{document}

you thus get

---

If you only want this special format for \fullcite, move the four \DeclareNameAlias lines into the pre-code hook of \usedriver in \DeclareCiteCommand{\fullcite} like so

\DeclareCiteCommand{\fullcite}
  {\usebibmacro{prenote}}
  {\usedriver
     {\DeclareNameAlias{sortname}{given-family-etal}%
      \DeclareNameAlias{author}{given-family-etal}%
      \DeclareNameAlias{editor}{given-family-etal}%
      \DeclareNameAlias{translator}{given-family-etal}}
     {\thefield{entrytype}}}
  {\multicitedelim}
  {\usebibmacro{postnote}}

If you want to define a special command for that so that you can use 'normal' \fullcite and the new name format simultaneously, you could define a starred \fullcite* via

\DeclareCiteCommand*{\fullcite}
  {\usebibmacro{prenote}}
  {\usedriver
     {\DeclareNameAlias{sortname}{given-family-etal}%
      \DeclareNameAlias{author}{given-family-etal}%
      \DeclareNameAlias{editor}{given-family-etal}%
      \DeclareNameAlias{translator}{given-family-etal}}
     {\thefield{entrytype}}}
  {\multicitedelim}
  {\usebibmacro{postnote}}

instead.

---

If you want to 'filter' several names (additionally also, say {Tajima}, T.), you can combine the hash comparisons into one \ifboolexpr. Just use

\ifboolexpr{test {\iffieldequalstr{hash}{f9c1127a739dfe7ad337f89c98aebf51}}
            or 
            test {\iffieldequalstr{hash}{67bbebbc19c3d65d07202eac52047d5e}}}%% <----- put the correct hash here

instead of \iffieldequalstr{hash}{f9c1127a739dfe7ad337f89c98aebf51} in \DeclareNameFormat{given-family-etal}:

\DeclareNameFormat{given-family-etal}{%
  \letbibmacro{name:delim}{name:etal:delim}%
  \ifnumcomp{\value{listcount}}{=}{1}
    {\setcounter{namesnotimportant}{0}%
     \global\toggletrue{ellipsis}}
    {}%
  \ifboolexpr{test {\ifnumcomp{\value{listcount}}{=}{1}}
              or test {\ifnumcomp{\value{listtotal}}{=}{2}}}
    {\ifgiveninits
      {\usebibmacro{name:given-family}
         {\namepartfamily}
         {\namepartgiveni}
         {\namepartprefix}
         {\namepartsuffix}}
      {\usebibmacro{name:given-family}
         {\namepartfamily}
         {\namepartgiven}
         {\namepartprefix}
         {\namepartsuffix}}}%
    {\ifboolexpr{test {\iffieldequalstr{hash}{f9c1127a739dfe7ad337f89c98aebf51}}
                 or 
                 test {\iffieldequalstr{hash}{67bbebbc19c3d65d07202eac52047d5e}}}%% <----- put the correct hash here
      {\global\toggletrue{ellipsis}%
       \ifgiveninits
        {\usebibmacro{name:given-family}
           {\namepartfamily}
           {\namepartgiveni}
           {\namepartprefix}
           {\namepartsuffix}}
        {\usebibmacro{name:given-family}
           {\namepartfamily}
           {\namepartgiven}
           {\namepartprefix}
           {\namepartsuffix}}}%
      {\stepcounter{namesnotimportant}%
       \iftoggle{ellipsis}
         {\addcomma\space\textellipsis\global\togglefalse{ellipsis}\isdot}
         {}}}%
  \ifboolexpr{
    test {\ifnumequal{\value{listcount}}{\value{liststop}}}
    and
    (test \ifmorenames
     or test {\ifnumcomp{\value{namesnotimportant}}{>}{0}})
  }
    {\andothersdelim\bibstring{andothers}}
    {}}