\RequirePackage[backend=biber, citestyle=numeric-comp, bibstyle=multiple-dm, sorting=ymdtn, maxbibnames=99, defernumbers=true, giveninits=true, sortcites]{biblatex}
% Patch endyears that are not declared
+% http://tex.stackexchange.com/a/327884/7561
\DeclareSourcemap{
\maps[datatype=bibtex]{
\map{
- \step[fieldsource=year]
- \step[fieldset=endyear, origfieldval]
+ \step[fieldsource=date, match=\regexp{\A([0-9]{4}-[0-9]{2}-[0-9]{2})\Z}, replace=\regexp{$1/$1}]
+ \step[fieldsource=date, match=\regexp{\A([0-9]{4}-[0-9]{2})\Z}, replace=\regexp{$1/$1}]
+ \step[fieldsource=date, match=\regexp{\A([0-9]{4})\Z}, replace=\regexp{$1/$1}]
}
}
}