biblatex: stop supressing double punctuation after title which ends with a dot

Question

I have a problem with the automatic punctuation while using \footcite:

• I use references whith titles ending with a dot (e.g. 'Die Reichstuerkenhilfe in der Zeit Karls V.'). The dot is part of the title and has to be part of the citation.
• When I cite several titles, the titles are separated by semicolons (;), and when I add some information after a cited title, this is separated from the title by a comma (,).
• My problem is: When I cite a title with a dot in the end, the semicolon or comma is automaticly supressed.

How can I make biblatex showing both, the dot, which ist part of the cited title, and the semicolon or comma, which indicate the end of the title? There has to be a mechanism which prohibits several punctuation signs without space in between.

This is the biblatex part of my document's head:

\usepackage[backend=biber,
                    style=authortitle-dw,
                    namefont=smallcaps,
                    idembib=false,
                    idemtracker=false,
                    ibidtracker=false,
                    edbyidem=false,
                    edsuper=true,
                    sortlocale=de_DE,
                    url=false, 
                    doi=true,
                    eprint=false]
                    {biblatex}


\renewcommand*{\labelnamepunct}{\addcomma\space } 
\renewcommand*{\nametitledelim}{\addcomma\space } 
\renewcommand*{\newunitpunct}{\addcomma\space }