[Tex/LaTex] leftskip, rightskip and centering in reledmac

Question

I try to use \leftskip and \rightskip together with \pstart and \pend in reledmac.
My goal is to set titles centered and have the left and right margin increased. This is what I have so far:

\documentclass{scrbook}
\usepackage{reledmac}
\begin{document}
\beginnumbering
\rightskip=3em
\leftskip=3em
{\centering\pstart Romeo and Juliet \pend}
{\centering\pstart (First performance by the  Theatre in the Winter 1564, played by Shakespeare and his company the Lord Chamberlain’s Men)\pend}
\rightskip=0em
\leftskip=0em
\pstart Romeo and Juliet is a tragedy written by William Shakespeare early in his career about two young star-crossed lovers whose deaths ultimately reconcile their feuding families. It was among Shakespeare's most popular plays during his lifetime and, along with Hamlet, is one of his most frequently performed plays. Today, the title characters are regarded as archetypal young lovers.
\pend
{}\endnumbering
 \end{document}

Unfortunately the title and subtitle are not responding to the skip-commands. I know I could use the eledchapter etc.-commands but that would mean I would have to totally rewrite them as i need no space before and after, nothing in the toc, no space between heading and subheading and text etc. etc.

Answer 1

Move \rightskip and \leftskip after \pstart. The latter resets these values. Like this:

\documentclass{scrbook}
\usepackage{reledmac}
\begin{document}
\beginnumbering
\pstart\noindent\centering
  Romeo and Juliet
\pend
\pstart\noindent\leftskip=3em plus1fill\rightskip\leftskip
  (First performance by the  Theatre in the Winter 1564,
  played by Shakespeare and his company the Lord Chamberlain’s Men)
\pend
\medskip
\pstart
  Romeo and Juliet is a tragedy written by William Shakespeare
  early in his career about two young star-crossed lovers whose deaths
  ultimately reconcile their feuding families. It was among
  Shakespeare's most popular plays during his lifetime and, along with
  Hamlet, is one of his most frequently performed plays. Today, the
  title characters are regarded as archetypal young lovers.
\pend
\endnumbering
\end{document}