The planetary orbits in the solar system are vastly smaller than the typical distance between stars in the combined Milky-Way-Andromeda system. The only difference will be a slightly higher typical speed for Andromeda stars compared to the relative motion of stars in the Milky Way disk. But that's only by like a factor of 10, and I don't have any reason to think that will cause a perturbation that's noticeable above the normal uncertainty from chaos in planetary orbits.
