Orbital decay for merged dwarf galaxies (left) and satellites that survived (right) for each M 31 and MW analogue in the HESTIA simulations. The satellites that survived are the dwarf galaxies inside the virial radius of the main progenitor, which are still gravitationally bound to their own sub-halo at z = 0. Mergers correspond to the galaxies that, at some point in the evolution, become unbound and were disrupted inside the main progenitor. We note that some of these galaxies become unbound well before their mass centre reaches the centre of the main progenitor.