I am re-typesetting an old book that has long footnotes, many of which include block quotations. It's our policy to keep the broad layout as faithful as possible to the original, so converting footnotes to endnotes is not an option, nor is moving the block quotations inline. Our house style uses hanging footnotes, of the sort produced by the [hang] option to the footmisc package. For the purpose of this question, let's assume these are non-negotiable requirements.
Here's a MWE of what a typical page might look like:
\documentclass[a4paper,11pt,oneside]{book}
\usepackage{lipsum}
\usepackage[hang]{footmisc}
% Use indented paragraphs in footnotes
\edef\hangfootparskip{\the\parskip}
\edef\hangfootparindent{\the\parindent}
\addtolength{\footnotesep}{\partopsep}
\begin{document}
\lipsum[1]\footnote{%
\lipsum[3][1-8]
\begin{quotation}
\lipsum[3][1-3]
\end{quotation}
\lipsum[3][9-12]
\lipsum[3][13-15]
}
\begin{quotation}
\lipsum[2]
\end{quotation}
\lipsum[4][1-5]\footnote{\lipsum[5][1-4]}
\lipsum[6][1-8]
\end{document}
If you generate a PDF, you'll see the quotation in the footnote is barely indented at all. That's because the quotation indent is only just more than the hanging footnote indent, and they appear not to be additive. What I'd really like is the footnote indentation to be indented by the normal quotation indent plus the footnote hanging indent.
I can increase the margin by patching the \quotation macro, but that affects uses in the body as well as the footer:
\usepackage{etoolbox}
\patchcmd\quotation{\rightmargin}{\leftmargin 4em \rightmargin}{}{}
I know I can also create a new environment for footnote quotations (though that seems unsatisfactory), which invokes \quotation and \endquotation directly, but then I don't know that I can patch it.
The standard quote and verse environments have them same problem, and ideally I'd like a solution that allows these to be used in the footnotes too. I've also briefly experimented with the quoting package, and it seems to have the same problem – though I'm not very familiar with this package so could be misusing it.
(I've left in our configuration to make footnote paragraphs indented rather than space-separated, in case it affects the answer. I'm not sure whether this is the best way of achieving this, but I'd rather not get into that here unless it's relevant to answering my question.)
I'm using XeLaTeX, in case that's relevant.
