biblatex-chicago: Separator between citations

Question

I am using the biblatex-chicago package for writing a paper for a journal, that requires footnote citations:

\usepackage[notes,natbib,isbn=false,backend=biber]{biblatex-chicago}  

However, I have a problem when it comes to citing two (or more) sources and adding some comments to them. For example, in this case:

\footcites[A argues 123. See][]{Zambernardi2011}[However, B believes 456. See][]{See2001} 

the output looks like this:

A argues 123. See A, Titel, Journal, Year; However, B believes 456. See B, Titel, Journal Year.

What I need is a different separator after the citation of A2003. I do not want to have a semicolon, but a period!

@article{Zambernardi2011,
    Author = {Zambernardi, Lorenzo},
    Date-Added = {2017-04-20 12:58:28 +0000},
    Date-Modified = {2017-04-20 12:59:41 +0000},
    Journal = {Review of International Studies},
    Number = {3},
    Pages = {1335-1356},
    Title = {The impotence of power: Morgenthau's critique of American intervention in Vietnam},
    Volume = {37},
    Year = {2011}}

@article{See2001,
    Author = {See, Jennifer W.},
    Date-Added = {2017-04-20 12:57:29 +0000},
    Date-Modified = {2017-04-20 12:58:22 +0000},
    Journal = {Pacific Historical Review},
    Number = {3},
    Pages = {419-447},
    Title = {A Prophet Without Honor: Hans Morgenthau and the War in Vietnam, 1955-1965},
    Volume = {70},
    Year = {2001}}

Answer 1

I'm still not quite sure why you wouldn't see long and short citations with \cite, but does this give the output you want? I think it's more readable than using \footcites. And it does give you the period where you want it. (Note that this is @moewe's alternative answer above, but presented with code and output).

\documentclass{article}
\usepackage[notes,natbib,isbn=false,backend=biber]{biblatex-chicago}  
\usepackage{filecontents}
\begin{filecontents}{\jobname.bib}
@article{Zambernardi2011,
  Author = {Zambernardi, Lorenzo},
  Date-Added = {2017-04-20 12:58:28 +0000},
  Date-Modified = {2017-04-20 12:59:41 +0000},
  Journal = {Review of International Studies},
  Number = {3},
  Pages = {1335-1356},
  Title = {The impotence of power: Morgenthau's critique of American intervention in Vietnam},
  Volume = {37},
  Year = {2011}
}
@article{See2001,
  Author = {See, Jennifer W.},
  Date-Added = {2017-04-20 12:57:29 +0000},
  Date-Modified = {2017-04-20 12:58:22 +0000},
  Journal = {Pacific Historical Review},
  Number = {3},
  Pages = {419-447},
  Title = {A Prophet Without Honor: Hans Morgenthau and the War in Vietnam, 1955--1965},
  Volume = {70},
  Year = {2001}
}
\end{filecontents}
\addbibresource{\jobname.bib}
\pagestyle{empty}
\begin{document}
\null\vfill
First Citation.\footnote{\citeauthor{Zambernardi2011} argues 123. See
\cite{Zambernardi2011}. However, \citeauthor{See2001} believes 456. See
\cite{See2001}.}

Subsequent citation.\footnote{\citeauthor{Zambernardi2011} argues 123. See
\cite{Zambernardi2011}. However, \citeauthor{See2001} believes 456. See
\cite{See2001}.}

\printbibliography
\end{document}

Answer 2

The separator between to citations is called \multicitedelim, you can redefine it to be a full stop with

\renewcommand*{\multicitedelim}{\addperiod\space}

---

Since \multicitedelim is not set with \setunit but directly, it is hard to correct a wrong delimiter choice later on. Since the delimiter is set at a point where we can't know if the next citation has a pre-note we can't condition on that easily either.

So at the moment you can either manually switch \multicitedelim to \addperiod\space locally with

\AtNextCite{\renewcommand*{\multicitedelim}{\addperiod\space}}

before citations where you need a full stop.

Or you use \footnote directly. If your text is longer that becomes a very attractive option.

\footnote{A argues 123. \cite[See][]{sigfridsson}. However, B believes 456. \[See][]cite{worman}}

The pre-note argument is quite well-suited for short introductory 'remarks' like 'cf.', 'see', but not so much for longer discussions.