Custom compound labeling with chemstyle

Question

Even though I made extensive use of the help given from this forum, it's the first time I actually ask a question, so I hope to not mess it up :)

I'm writing my chemistry project proposal with LaTeX, but I'm no expert user. I use the chemstyle package to number compounds and everything works just fine. However, I'd like to swap the numbers with a custom label (I don't know, EG1 for instance). How could I do that?

Even more complicated, would it be possible to have two separate series of compounds going together in parallel? One where the numbering goes as usual and one with a custom label.

What I'm trying to do is to use the normal numbering in the background part of the proposal, where I refer to literature compounds (which I would like to number as 1,2,3...), whereas I'd like to use the custom labeling for the compounds I will be synthesizing (EG1, EG2...).

Hope the question is not too vague and I explained my problem clearly enough.

EDIT: I've added a MWE as suggested. I couldn't upload the EPS files, so I linked the overleaf document where the files are.

    \documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage[english]{babel}
\usepackage{psfrag}
\usepackage[journal=rsc]{chemstyle}
\usepackage{graphicx}

\begin{document}
\begin{figure}
\schemeref{1}
\schemeref{2}
\schemeref{3}
\includegraphics[width=0.8\linewidth]{Screening_hits}
\caption{Compounds with normal numbering}
\end{figure}

\begin{figure}
\schemeref{EG1}
\schemeref{EG2}
\schemeref{EG3}
\schemeref{EG4}
\includegraphics[width=0.8\linewidth]{MWE_custom}
\caption{Compounds with indipendent, custom numbering}
\end{figure}

\end{document}

The above code gives this result, which is not quite what I want to achieve.

MWE on overleaf