Tikz, alcance escalado y nodo compartido

Question

Para incluir una pequeña subfigura en mi figura principal, intenté usar un alcance escalado. Sin embargo, cuando intento hacer referencia a un nodo fuera del alcance escalado, el nodo señalado está en la posición del antiguo nodo no escalado... Aquí hay una imagen:

¿Sabes cómo evitar eso?

Gracias !

PD: Aquí está mi WME.

\documentclass{report}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage[francais]{babel}     
\usepackage{float}
\usepackage{tikz}
\usetikzlibrary{shapes.geometric,arrows}
\usetikzlibrary{mindmap,backgrounds,positioning}
\usetikzlibrary{automata,positioning,fit,backgrounds}
\usetikzlibrary{positioning,arrows,matrix,calc}

\begin{document}

\begin{figure}[H]
  \centering
  \begin{tikzpicture}
    \begin{scope}[transform canvas={scale=1},overlay]
      \node[fill=green]   (a) {A};
      \node[fill=green,right=of a] (b) {B};
    \end{scope}
    \node[draw,below=5mm of b] (c) {C};
    \draw[<->] (c) -- (b);
  \end{tikzpicture}%
  \hspace{3cm}%
  \begin{tikzpicture}
    \begin{scope}[transform canvas={scale=0.2},overlay]
      \node[fill=green]   (a) {A};
      \node[fill=green,right=of a] (b) {B};
    \end{scope}
    \node[draw,below=5mm of b] (c) {C};
    \draw[<->] (c) -- (b);
  \end{tikzpicture}%
\end{figure}

\end{document}

Answer 1

¿Quizás quieras esto?

\documentclass{report}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage[francais]{babel}
\usepackage{tikz}
\usetikzlibrary{positioning,babel}

\begin{document}

\begin{figure}
  \centering
  \begin{tikzpicture}
    \node[fill=green]   (a) {A};
    \node[fill=green,right=of a] (b) {B};
    \node[draw,below=5mm of b] (c) {C};
    \draw[<->] (c) -- (b);
  \end{tikzpicture}
  \hspace{3cm}
  \begin{tikzpicture}
    \begin{scope}[scale=0.2, every node/.append style={transform shape}]
      \node [fill=green]   (a) {A};
      \node [fill=green,right=of a] (b) {B};
    \end{scope}
    \node [draw,below=5mm of b] (c) {C};
    \draw [<->] (c) -- (b);
  \end{tikzpicture}
\end{figure}

\end{document}