Temporal evolution of the fraction of N-body particles that stay bound to the progenitor (M1 = red, M2 = green). We checked that the formula of Varghese et al. (2011) for the Jacobi radius was a good approximation in MOND too, and used it to determine if particles are bound. We note how the progenitor in the M1 case significantly increases its mass between t = 2.7 Gyr and t = 3 Gyr, through the increase of the Roche radius, allowing it to recover the stars that stay close to it. We also highlight how the large pericenter of the M2 orbit at t ≈ 2.4 Gyr limits the mass loss in simulation M2. It is interesting how these effects conspire to give a very realistic remnant in both simulations, as shown in Fig. 5.