Expandable Nested Boxes with TikZ

The shapes.multipart library of TikZ can be helpful (refer to Section 48.6 Shapes with Multiple Text Parts of the pgfmanual); a little example:

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{shapes.multipart}

\begin{document}

\begin{tikzpicture}[
  double/.style={draw, anchor=text, rectangle split,rectangle split parts=2},
  triple/.style={draw, anchor=text, rectangle split,rectangle split parts=3}
  ]
  \node[triple] {foo
    \nodepart{second}
      bar
    \nodepart{third}
      \tikz{\node[double] {\nodepart{second}baz};}
  };

  \node[triple] at (2.2,0) {some text here
    \nodepart{second}
      bar
    \nodepart{third}
      \tikz{\node[double] {\nodepart{second}some more text goes here};}
  };

  \node[double,align=center] at (7.5,0) {some text here
    \nodepart{second}
      bar \\
      \tikz{\node[double,align=center] {\nodepart{second}some more text\\ goes here};}
  };

\end{tikzpicture}

\end{document}

Do you know about the drs package? (I assuming you want to construct discourse representation structures and tikz itself isn't a requirement.)

\documentclass{article}
\usepackage{drs}
\begin{document}
\drs{X}{ the lawyers(X) \\ 
   \qdrs{x}{x $\in$ X}
        {every}{x} 
        {y}{secretary(y) \\ x hired y}}
\end{document}