Chemfig: How to get multiple arrows to one compound

Question

I'm very new to the ChemFig package. I would like to generate the following reaction scheme:

I'm having trouble coding the first four reactants that all lead to the \emptyset. This is what I've attempted so far:

\schemestart

\subscheme{$D\+L$}\arrow(dl--emp){->[*{0}$k_{15}$]}[-45]$\emptyset$

\arrow(@emp--b){->[$\mu$]}$B$\arrow(@b--s){->[$p_2$]}$S$\arrow(@s--hli){->[$k_9$]}$H\+L\+I$

\arrow(@emp--x){->[*{0}$\gamma$]}[45]$X$

\schemestop

Answer 1

\documentclass{article}
\usepackage{chemfig}
\begin{document}
\schemestart
\subscheme{
\subscheme{D + L}
\arrow(a--b){0}[-90,0.3]
\subscheme{I + H}
\arrow{0}[-90,0.3]
\subscheme{I \phantom{+} \phantom{H}}
\arrow(c--d){0}[-90,0.3]
\subscheme{A + E}
}
\arrow(--emp){0}
\(\emptyset\)
\arrow
B
\arrow
S
\arrow
H + L + I
\arrow(@a.mid [email protected] west)
\arrow(@b.mid [email protected] west)
\arrow(@c.mid [email protected] west)
\arrow(@d.mid [email protected] west)
\arrow(@emp.mid east--)[45]
X
\arrow(@emp.mid east--.mid west)[-45]
\subscheme{Bc + I}
\schemestop
\end{document}

Answer 2

A simpler version with fewer commands.

\documentclass[margin={2mm 4mm}]{standalone}
\usepackage{chemfig}

\begin{document}
    
\schemestart
%
\chemfig{@{a}\emptyset @{b}}
%
\arrow{->}[0,1.5] B \arrow{->}[0,1] S \arrow{->}[0,1] H + L + I
%
\arrow(@{a}--){<-}[120,1]\subscheme{D + L}
\arrow(@{a}--){<-}[160,1]\subscheme{I + H}
\arrow(@{a}--){<-}[200,1]\subscheme{I}
\arrow(@{a}--){<-}[240,1]\subscheme{A + E}
\arrow(@{b}--){->}[60,1]\subscheme{X}
\arrow(@{b}--){->}[300,1]\subscheme{Bc + I}
\schemestop

\end{document}