If we remember an event absolutely and clearly, then all paths to the present must lead through that event. If we do not remember an event clearly, it means that the details of the event can change, and those multiple configurations are the multiple paths that lead to the present.
Furthermore, multimnemism says that our mood, or mental state, defines what we can remember and therefore what paths or pasts we have.
It may be true that multimnemism and multirespism are in fact equivalent. This would lead us to question why the past and future seem like such different things.