I am having my biblatex defaults to switch to 'et al.' rather late (past three authors). Now I have occasions where the repeated mention of an author asks for a short form 'Author et al.', irrespective of the number of co-authors. I already use a custom name format like this:
\DeclareNameFormat{idem}{%
\usebibmacro{name:last}{#1}{#3}{#5}{#7}%
\usebibmacro{name:andothers}}
How would I create another name format, say with \DeclareNameFormat{short} that always resorts to 'et al.' if there is more than one author; without changing my global biblatex style settings (maxnames -- don't want to touch it!). Is there any other macro than name:andothers that I can use?
The answer of @lockstep gets close. But I want to have \citeauthor{A01} behave normally, except for cases where I repeat the authors multiple times. I can of course add a duplicate entry with this technique; still I wonder if I can get the following 'naive' idea taken from that answer to work:
\newcommand{\personshort}[1]{\defcounter{maxnames}{1}\citeauthor{#1}}
This 'works' but seems to overwrite maxnames for the rest of the document. how would I encapsulate the defcounter to be effective only inside this \newcommand?

defcounterseems to do the trick, but can I use it within a dedicated command instead of adding particular bibliography entries to a category (see my edited question)? – Emit Taste Jun 26 '12 at 10:10