Is it possible to add \chapter after a few \part's at the same level of hierarchy?

Question

Consider the following code:

\documentclass{scrbook}
\usepackage[bookmarks, bookmarkstype=toc]{hyperref}

\begin{document}

\tableofcontents

\chapter{Introduction}

\part{First part}
    \chapter{First chapter}
    \chapter{Second chapter}

\part{Second part}
    \chapter{Third chapter}
    \chapter{Fourth chapter}

\chapter{Conclusion}

\end{document}

In the resulting PDF both tables of contents (the one produced by \tableofcontents and the list of PDF bookmarks) have the following hierarchy:

Introduction
First part
- First chapter
- Second chapter
Second part
- Third chapter
- Fourth chapter
- Conclusion

Is it possible to put 'Conclusion' at the same level of hierarchy with 'Introduction', 'First part' and 'Second part'?

Answer 1

If you want to adapt only the bookmarks: Either use bookmark instead of hyperref (it will load hyperref internally)

\usepackage{bookmark}
...

\bookmarksetup{startatroot}
\chapter{conclusion}

Or

\makeatletter
\def\toclevel@chapter{-1}
\makeatother
\chapter{Conclusion}

Answer 2

\chapter*{Conclusion}
\addcontentsline{toc}{part}{Conclusion}

Answer 3

If you want to add a "Conclusion" that is at the same level of hierarchy as your "First part" and your "Second part", then I suggest to use \part*{Conclusion}.