  We focus on the evidence of a past minor merger discovered in the halo of the
Andromeda galaxy (M31). Previous N-body studies have enjoyed moderate success
in producing the observed giant stellar stream (GSS) and stellar shells in
M31's halo. The observed distribution of stars in the halo of M31 shows an
asymmetric surface brightness profile across the GSS; however, the effect of
the morphology of the progenitor galaxy on the internal structure of the GSS
requires further investigation in theoretical studies. To investigate the
physical connection between the characteristic surface brightness in the GSS
and the morphology of the progenitor dwarf galaxy, we systematically vary the
thickness, rotation velocity and initial inclination of the disc dwarf galaxy
in N-body simulations. The formation of the observed structures appears to be
dominated by the progenitor's rotation. Besides reproducing the observed GSS
and two shells in detail, we predict additional structures for further
observations. We predict the detectability of the progenitor's stellar core in
the phase-space density distribution, azimuthal metallicity gradient of the
western shell-like structure and an additional extended shell in the
north-western direction that may constrain the properties of the progenitor
galaxy.
