add "joint work with"

[Andrej Depperschmidt <depperand@gmail.com>]

Hello emacs-orgmode list!

I am trying to prepare a talk using ox-beamer and am missing a function
that I am used to.

In beamer latex one can for example write

\author[speaker]{speaker \\ joint work with second author and third author}

Then I get my name and that of my coauthors on the titlepage. My name
can then also appear (depending on the beamer theme) in the footnote on
each slide.

Is it possible to achieve this without exporting to latex and adjusting
the corresponding entries there?

I didn't find an answer on the list. Also in ox-beamer.el the
corresponding section contains only entries with \author{...}, i.e.
without square brackets. Would be nice to have an entry

#+COAUTHOR: second author and third author

that is then put in \author[second author and third author]{...}

Or is there already something similar that I didn't find?

Best regards,
Andrej