Impact of the most significant mergers and close pericentric passages of massive satellites on the orbital parameters of the in situ stars in M 31 and MW HESTIA galaxies. For each galaxy, in the top panels we highlight the time of the close passages (< 10 kpc from the host) and the stellar mass (M_impact at the time of the close passage) of the dwarf galaxies which either merged (red) or survived at z = 0 (blue). The two panels below show Z_max and Z_max/R_max as a function of the stellar age for three galactocentric regions: (0 − 1) R_d (blue), (1 − 2) R_d (red), and (2 − 3) R_d (green), where R_d is the disc scale length at z = 0.