I have modified the \part command style in a memoir document as in the following minimal example:
\documentclass[b5paper,10pt,twoside,openright,final,english]{memoir}
\usepackage{lipsum}
\usepackage[english]{babel}
\makepagestyle{part}
\makeevenfoot{part}{}{}{}
\makeoddfoot{part}{}{}{}
\makeevenhead{part}{}{}{}
\makeoddhead{part}{}{}{}
\renewcommand*{\beforepartskip}{\null\vskip 0pt plus -0.3fil}
\renewcommand*{\midpartskip}{\par\vskip 0pt plus 1.0fil}
\renewcommand{\printpartname}{\partnamefont\raggedleft Part}
\renewcommand*{\cftpartname}{Parte\space}
\renewcommand{\printpartnum}{\partnamefont\thepart \\ \vspace{-15pt} \hrulefill}
\begin{document}
\tableofcontents
\chapter{Introduction}
\lipsum
\part{Basics}
\chapter{A Chapter}
\lipsum
\appendix
\renewcommand*{\beforepartskip}{\null\vspace{.5\textheight}}
\renewcommand*{\midpartskip}{\par\vspace 2\onelineskip}
\renewcommand*{\printpartname}{\reggedleft\partname}
\part*{Appendix}
\chapter{An Appendix}
\lipsum
\end{document}
Why in the blank page relative to the \part* command the title "Appendix" is not flushright? In other words, I would like to change the \part style after appendix in such a way that the title "Appendix" in the blank page is flushright (in the middle of the page). How to do this?