Can multi-Book Memoir-class documents forgo Parts without breaking bookmarks?

Question

I wish to create a multi-Book Memoir-class document without the need for Part sections. Doing so breaks the bookmarks appearing in the PDF document. E.g., if I have a document such as

\documentclass{memoir}
\begin{document}
\book{Book1}
 %\part{Part1}
  \chapter{Chapter1}
  \chapter{Chapter2}
  \chapter{Chapter3}
\end{document}

the PDF's "chapter" bookmarks are structured like

• Book1
  • Chapter1
    • Charper2
    • Charper3

instead of the expected

• Book1
  • Chapter1
  • Charper2
  • Charper3

I noticed that by uncommenting the Part section in the above MWE, the chapter bookmarks are correctly structured:

• Book1
  • Part1
    • Charper1
    • Charper2
    • Charper3

Is there a way to forgo Parts and still get properly indented "chapter" bookmarks?

Answer 1

If I add the hyperref package to your MWE, the new bookmark structure is wrong indeed:

\documentclass{memoir}
\usepackage{hyperref}
\begin{document}
\book{Book1}
 %\part{Part1}
  \chapter{Chapter1}
  \chapter{Chapter2}
  \chapter{Chapter3}
\end{document}

The solution is to load the bookmark package:

\documentclass{memoir}
\usepackage{hyperref}
\usepackage{bookmark}
\begin{document}
\book{Book1}
 %\part{Part1}
  \chapter{Chapter1}
  \chapter{Chapter2}
  \chapter{Chapter3}
\end{document}