Arrangement of satellite system in the Milky Way and the Milky Way-like simulated galaxies, and relation with the 3D shape of DM halo. Left: the configuration of satellite system of each galaxy is characterised by two parameters: the fraction of satellites moving on vertical orbits f_{Sats,verticai}, and the azimuthal anisotropy of the satellite distribution ξ_Sat,φ. Each dot is one galaxy coloured by their DM halo shape q_DM - p_DM (< 50 kpc). The red star represents the Milky Way. The 13 TNG50/Auriga galaxies having DM halo shapes within 3σ confidence level of the Milky Way are highlighted. Right: correlation of the DM halo shape q_DM - p_DM versus satellite distribution f_{Sats,vertical} of the 94 TNG50 galaxies, R in the legend is the Pearson correlation coefficiant. The correlation becomes stronger when increasing the number of satellites by taking a lower mass threshold and measuring DM shape at a larger radius.