The ΛCDM model predicts a hierarchical formation for galaxies: the merging history is thus crucial to understand how they form and evolve. In the last twenty years, many accreted substructures have been found in the Galactic halo, identified as stellar over-densities in specific regions of kinematics-related spaces with different chemical properties. We analysed the outcomes of high-resolution N-body simulations, which modelled a Milky Way-type galaxy accreting a satellite with mass ratio 1:10, with different orbital parameters and initial metallicity gradients, in order to check whether these methods were solid or not. We found that energy and angular momentum are not generally conserved for such a massive satellite, due to the dynamical friction, thus resulting in the satellite stars redistributing over a large fraction of the E − Lz space. As a consequence, different regions of the E − Lz can feature different metallicity distribution functions (MDFs) even if caused by a single satellite merger event, due to the initial metallicity gradients. Nevertheless, we found some solid trends in the global properties of the MDFs when moving throughout the E − Lz space. This global coherence could be exploited to interpret the observational data, fact that would be crucial now, given the unprecedented data flow, driven by the Gaia mission and the complementary spectroscopic surveys.