  A new approach for obtaining the three-dimensional Chern-Simons supergravity
for the Poincar\'e algebra is presented. The $\mathcal{N}$-extended Poincar\'e
supergravity is obtained by expanding the super Lorentz theory. We extend our
procedure to their respective asymptotic symmetries and show that the
$\mathcal{N}=(1,2,4)$ super-BMS$_{3}$ appear as expansions of one Virasoro
superalgebra. Interestingly, the $\mathcal{N}$-extended super-BMS$_{3}$
obtained here are not only centrally extended but also endowed with internal
symmetry. We also show that the $\mathcal{N}$-extended super Poincar\'e
algebras with both central and automorphism generators are finite subalgebras.
