Beamer Overlay Specifications: How to keep uncovered items in place when using only for subitems?

Question

Is there a way in this MWE to keep the first item in place when displaying the subitems? The idea is that I have several items on the slide that I want to uncover one-by-one, each time elaborating on the item with additional subitems that are supposed to disappear again. I find it distracting when the items change positions.

\documentclass{beamer}
\begin{document}
\begin{frame}{Frame Title}
    \begin{itemize}
        \item<1-> xxxx
        \begin{itemize}
            \item<only@2> xyz
            \item<only@2> xyz
            \item<only@2> xyz
            \item<only@2> xyz
        \end{itemize}
        \item<3-> xxx
    \end{itemize}
\end{frame}
\end{document}

Answer 1

You could use an overlayarea of suitable height (change .5\textheight to whatever height your items require):

\documentclass{beamer}
\begin{document}
\begin{frame}{Frame Title}
    \begin{overlayarea}{\textwidth}{.5\textheight}
    \begin{itemize}
        \item<1-> xxxx
        \begin{itemize}
            \item<only@2> xyz
            \item<only@2> xyz
            \item<only@2> xyz
            \item<only@2> xyz
        \end{itemize}
        \item<3-> xxx
    \end{itemize}
    \end{overlayarea}
\end{frame}
\end{document}