[Tex/LaTex] Appendices merged into the last “part”

Question

I'm writing my Thesis using TeXnicCentre 2.02 and MiKTeX 2.9.
I found a small issue that I can't fix…

I'm using some parts in the document, and it happens that the appendices are inside the last part. I've tried to use \backmatter without success. Can you give me a piece of advice?

A part of my preamble:

\documentclass[11pt,openright,twoside]{toptesi}
...
\usepackage{indentfirst}
\usepackage[toc]{appendix}
\usepackage[colorlinks=false, pdfborder={0 0 0}]{hyperref}
\usepackage{nameref}
...

%% Document Parts %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{document}

\include{Cpt_0}
\include{Cpt_1}
\part{Part 1}
... some chapters ...
\part{Part 2}
\include{Cpt_2}
\include{Cpt_3}

\appendix
\appendixpage
\addappheadtotoc

\include{App_1}
\include{App_2}
\include{App_3}

\printbibliography
\end{document}

Answer 1

A suggestion for a solution: Use the Appendix as a part to get the structuring consistent.

I assumed, that \include{App_1} etc. contain \chapter commands.

\documentclass[11pt,openright,twoside]{toptesi}

\usepackage{indentfirst}
%\usepackage[toc]{appendix}
\usepackage[colorlinks=false, pdfborder={0 0 0}]{hyperref}
\usepackage{biblatex}
\usepackage{nameref}

%% Document Parts %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{document}
\tableofcontents%

%\include{Cpt_0}
%\include{Cpt_1}
\part{Part 1}
... some chapters ...
\part{Part 2}
%\include{Cpt_2}
%\include{Cpt_3}


\setcounter{chapter}{0}%
\renewcommand{\thechapter}{\Alph{chapter}}%  Letters as 'counters'
\part{\appendixname}

\chapter{First Appendix}
\chapter{Second Appendix}
\chapter{Third Appendix}

%\include{App_1}
%\include{App_2}
%\include{App_3}

\printbibliography
\end{document}