Problem with "numcases"

Something like this?

\documentclass[11pt,a4paper]{report}
\usepackage{amsmath}
\usepackage{cases}
\newcommand{\mydots}{\dots\dots}
\begin{document}
\begin{numcases}{}
\mydots\\
\begin{aligned}
&\quad\mydots\\
&\qquad\mydots
\end{aligned}\\
\quad\mydots\\
\begin{aligned}
&\qquad\mydots\\
&\qquad\mydots
\end{aligned}\\
\quad\mydots
\end{numcases}
\end{document}

I'd use empheq that's much more powerful than cases.

Your requirement about equation numbers can be achieved by nesting aligned.

\documentclass{article}
\usepackage{empheq}

\begin{document}

\begin{empheq}[left=\empheqlbrace]{align}
& \mathstrut ..........
\label{e2.1}
\\
&\begin{aligned}
  &\quad.........\\
  &\qquad.........
\end{aligned}
\label{e2.2}
\\
&\begin{aligned}
  &\quad..........\\
  &\qquad..........\\
  &\qquad..........
\end{aligned}
\label{e2.3}
\\
&\begin{aligned}
  &\quad.........\\
  &\qquad.........
\end{aligned}
\label{e2.4}
\end{empheq}

\end{document}