Issue with Referencing Figures from Supplementary Information in LaTeX

Question

I am working on a LaTeX document where I have a main document and supplementary information (SI). In the SI, I want to maintain the sequence "Figure S1, Figure S2..." for labeling the figures. In the main document, I want to reference these figures from the SI using the \ref{} command, but I'm encountering some issues.

Here's a simplified version of my setup:

main.tex:

\documentclass{article}
\usepackage{graphicx}
\begin{document}
\section{Main Document}
\begin{figure}[htbp]
    \centering
    \includegraphics[width=0.5\textwidth]{example-image-a}
    \caption{Example A}
    \label{fig:example_a}
\end{figure}
\begin{figure}[htbp]
    \centering
    \includegraphics[width=0.5\textwidth]{example-image-b}
    \caption{Example B}
    \label{fig:example_b}
\end{figure}
Text in the main document attempting to call the figures from the Supplementary Information: Figure \ref{fig:example_c} and Figure \ref{fig:example_d}.
\end{document}

support_information.tex:

\documentclass{article}
\usepackage{graphicx}
\begin{document}
\section{Supplementary Information}
\begin{figure}[htbp]
    \centering
    \includegraphics[width=0.5\textwidth]{example-image-c}
    \caption{Example C}
    \label{fig:example_c}
\end{figure}

\end{document}

It is crucial that the sequence in both documents be distinct: 'Figure 1', 'Figure 2',... for the main document and 'Figure S1', 'Figure S2',... for the Supplementary Information.

Answer 1

This uses \include and \includeonly to combine both files, but only print one at a time.

\documentclass{article}
\usepackage{graphicx}
\includeonly{test5,test6}% print both
\begin{document}
\include{test6}% main text
\setcounter{page}{1}
\setcounter{section}{0}
\setcounter{figure}{0}
\renewcommand{\thefigure}{S\arabic{figure}}
\renewcommand{\thepage}{S\arabic{page}}
\include{test5}% supplemental
\end{document}

Stored as test6.tex:

\section{Main Document}
\begin{figure}[htbp]
    \centering
    \includegraphics[width=0.5\textwidth]{example-image-a}
    \caption{Example A}
    \label{fig:example_a}
\end{figure}
\begin{figure}[htbp]
    \centering
    \includegraphics[width=0.5\textwidth]{example-image-b}
    \caption{Example B}
    \label{fig:example_b}
\end{figure}
Text in the main document attempting to call the figures from the Supplementary Information: Figure \ref{fig:example_c}.

Stored as test5.tex

\section{Supplementary Information}
\begin{figure}[htbp]
    \centering
    \includegraphics[width=0.5\textwidth]{example-image-c}
    \caption{Example C}
    \label{fig:example_c}
\end{figure}

Answer 2

Two answers that could help

1. Change the figure captions

Change numbering of captions in figures

2. Use references from other documents

Cross-referencing between different files