System of equations numbering and cref

Question

I'm using the SIAM template, and I want numbering a system of equation 1a,1b,..., to label them and to be able to quote them thanks to the \cref command from the cleveref package.

I tried the different solutions proposed on this topic, which work for a minimal TeX example, but seem to crash with the SIAM template:

First solution

\usepackage{empheq}
\begin{subequations}
    \label{Phi:def}
      \begin{align}[left ={\phi A_n = \empheqlbrace}]
        & \max \left [ L_n-A_n, 0 \right]\\
        & \max \left [ L_n-A_n, K \right]\label{eq:PayoffStopLosses}\\
        & \max \left [ L_n-A_n, K_1 \right] -\max \left [ A_n-L_n, K_2 \right]
       \end{align}
\end{subequations}
Let's quote the second equation \cref{eq:PayoffStopLosses}

The quotation works, but the brace doesn't. If we add the package option overload, it works for a minimal example but not into the SIAM template:

/usr/local/texlive/2015/texmf-dist/tex/context/base/supp-pdf.mkii
[Loading MPS to PDF converter version 2006.09.02.]
\scratchcounter=\count150
\scratchdimen=\dimen147
\scratchbox=\box34
\nofMPsegments=\count151
\nofMParguments=\count152
\everyMPshowfont=\toks42
\MPscratchCnt=\count153
\MPscratchDim=\dimen148
\MPnumerator=\count154
\makeMPintoPDFobject=\count155
\everyMPtoPDFconversion=\toks43

LaTeX Info: Redefining \[ on input line 37.
LaTeX Info: Redefining \] on input line 37.
LaTeX Font Info:    Try loading font information for U+msa on input line 40.
 /usr/local/texlive/2015/texmf-dist/tex/latex/amsfonts/umsa.fd
File: umsa.fd 2013/01/14 v3.01 AMS symbols A

LaTeX Font Info:    Try loading font information for U+msb on input line 40.

/usr/local/texlive/2015/texm 

Second solution

\usepackage{cases}
\begin{subnumcases}{f x=}
       1 & $x\geq0$ \label{positive-subnum}
       \\
       0 & $x<0$ \label{negative-subnum}
\end{subnumcases}
Let's quote the second equation \cref{negative-subnum}

In this case, both "positive-subnum" and "negative-subnum" gives the same result "2" with the \cref command...

Have you any suggestion?

Answer 1

The following is an alteration of the first solution so the package option overload is no longer needed. It works in a minimal example, and also when I try it in the SIAM template.

\documentclass{article}
\usepackage{amsmath,empheq}
\usepackage[noabbrev]{cleveref}
\begin{document}
\begin{subequations}
    \label{Phi:def}
      \begin{empheq}[left ={\phi A_n = \empheqlbrace}]{align}
        & \max [ L_n-A_n, 0 ]\\
        & \max [ L_n-A_n, K ]\label{eq:PayoffStopLosses}\\
        & \max [ L_n-A_n, K_1 ] -\max [ A_n-L_n, K_2 ]
       \end{empheq}
\end{subequations}
Let's quote the second equation \cref{eq:PayoffStopLosses}
\end{document}