$MgS{O}_4$ on reaction with $N{H}_{4}OH$ and $N{a}_{2}HP{O}_4$ forms white crystalline precipitate. What is its formula

${\mathrm{MgSO}}_4$ on reaction with ${\mathrm{Na}}_2{\mathrm{HPO}}_4$ (disodium hydrogen phosphate) in presence of ${\mathrm{NH}}_4\mathrm{OH}$ to give white precipitate of magnesium ammonium phosphate $\left[\mathrm{Mg}\left({\mathrm{NH}}_4\right){\mathrm{PO}}_4\right]$

$$\begin{gathered} {\mathrm{MgSO}}_4+{\mathrm{Na}}_2{\mathrm{HPO}}_4+{\mathrm{NH}}_4\mathrm{OH}⟶ \\ \mathrm{Mg}\underset{white ppt.}{\left({\mathrm{NH}}_4\right){\mathrm{PO}}_4}\downarrow +{\mathrm{Na}}_2{\mathrm{SO}}_4+{\mathrm{H}}_2\mathrm{O} \end{gathered}$$