"And" between last and second last cite using the \footcites command and authoryear-icomp

Question

When using \footcites all cites are equally separated by \multicitedelim. However, I would like the last two cites to be separated by "and". With certain limitations, this is possible with \textcites and a workaround would be to use \footnote{\textcites{}.}. Strangely, this only works for two cites. If three or more cites are included ", and" and not "and" is produced. Considering this, I was wondering what would have to be done to obtain the desired result using \footcites.

Here is a minimal working example:

\documentclass{article}
\usepackage[style=authoryear-icomp]{biblatex}
\usepackage{filecontents}

\begin{filecontents}{references.bib}
@article{greenwade93,
    author  = {George D. Greenwade},
    title   = {The {C}omprehensive {T}ex {A}rchive {N}etwork ({CTAN})},
    year    = {1993},
    journal = {TUGBoat},
    volume  = {14},
    number  = {3},
    pages   = {342--351}
}
@book{goossens93,
    author    = {Michel Goossens and Frank Mittelbach and Alexander Samarin},
    title     = {The LaTeX Companion},
    year      = {1993},
    publisher = {Addison-Wesley},
    address   = {Reading, Massachusetts}
}

@book{Knuth86,
    author = {Knuth, Donald E.},
    year = {1986},
    title = {The \TeX book}
}
\end{filecontents}

\addbibresource{references.bib}
\begin{document}
How it should look like.\footnote{\cites{goossens93}{greenwade93} and \cite{Knuth86}.}

How it should not look like.\footcites{goossens93}{greenwade93}[and][]{Knuth86}
\printbibliography
\end{document}

Thanks a lot!

Answer 1

Luckily, biblatex already provides everything we need for this (so much so that I am surprised this is not actually already implemented - other \multi...delims already have \final...delim versions).

We just need to make use of biblatex's \iflastcitekey test to determine whether we are at the last item, and if so slightly change the definition of \multicitedlim

\renewcommand*{\multicitedelim}{%
  \iflastcitekey
    {\addspace\bibstring{and}}
    {\addsemicolon}%
  \space}

That's it!

This will not work in all comer cases (especially in case of compressed citations), in these cases it might be better to use \textcite in the footnote directly. Like

\footnote{\textcite{geer,knuth:ct:a,knuth:ct:b,knuth:ct:c}}

Depending on your stance on the Oxford comma you will need to tweak \finalandcomma/\finalandsemicolon.

MWE

\documentclass{article}
\usepackage[style=authoryear-icomp]{biblatex}
\addbibresource{biblatex-examples.bib}

\renewcommand*{\multicitedelim}{%
  \iflastcitekey
    {\addspace\bibstring{and}}
    {\addsemicolon}%
  \space}

\begin{document}
How it should look like.\footcites{geer}{sigfridsson}{worman} vs this\footcites{geer,sigfridsson,worman}
\printbibliography
\end{document}