How to get chemical equations with diagonal arrows

I have a small working example

\documentclass{article}

\usepackage{amsmath}
\usepackage[version=4]{mhchem}

\begin{document}
\begin{gather*}
\ce{
S + E_1 <=> SE_1 -> P + E_1 \\ S + E_2 <=> SE_2 -> P + E_2 %Ask how to do this on Stackxchange
}
\end{gather*}

\end{document}

This ends up giving 2 equation, but I want to merge these 2 equations together, into 1.

I am looking to have like have the S + E_1 <=> SE_1 and S + E_2 <=> SE_2 on the same line as each other (with only 1 S), but like at 45 degrees from the horizontal in both directions.

I'm really struggling to explain what I mean, but hopefully what I've put makes sense

Edit:This is what I mean https://gyazo.com/25902d106e90a628820075df6c023523

With the \ArrowBetweenLines command from mathtools:

\documentclass{article}

\usepackage{mathtools}
\usepackage[version=4]{mhchem}

\begin{document}

\begin{alignat*}{2}
\thickspace & \ce{E_1 <=> SE_1 -> P + E_1}\\
\ArrowBetweenLines[\ce{S}\enspace\renewcommand{\arraystretch}{0.9}\begin{matrix} + \\\\+\end{matrix}\!\!]& \ce{ E_2 <=> SE_2 -> P + E_2}
\end{alignat*}

\end{document} Using tikz may be an overkill, but here it is

\documentclass[]{article}
\usepackage{tikz}
\usetikzlibrary{positioning}

\begin{document}
\begin{tikzpicture}[inner sep = 0pt]
\node[] (S) {$S$};
\node[above right = 1pt and 3pt of S] {$+ E_1 \rightleftharpoons S E_1 \to P + E_1$};
\node[below right = 1pt and 3pt of S] {$+ E_2 \rightleftharpoons S E_2 \to P + E_2$};
\end{tikzpicture}

\end{document} • You may write ${} + E_1 \rightleftharpoons S E_1 \to P + E_1$ to have the right spacing around the first + (and similarly for the second equation). – user94293 Feb 12 '18 at 1:14

Using multirow:

\documentclass{article}

\usepackage{amsmath}
\usepackage{multirow}

\usepackage[version=4]{mhchem}

\begin{document}

\begin{alignat*}{2}
\multirow{2}{*}{\ce{S}}\thickspace & \ce{+ E_1 <=> SE_1 -> P + E_1}\\
& \ce{+ E_2 <=> SE_2 -> P + E_2}
\end{alignat*}

\end{document} 