The way it works is we live in a multi layered omniverse, which is everything that could possibly be, sorted into different layers, like folders and subfolders. The outermost layer is all that could possibly exist, which does exist. The second layer is made up of multiverses, each with their own unique set of natural laws, there is one multiverse for every unique set of natural laws that could possibly exist. The third layer is made up of timelines, each with their own unique series of universe configurations (and anti-universes) between singularities, from the universe's expansion from a singularity to its collapse back into one (and the series of anti universes that are the same but running in reversed time, from after the collapse back to before the expansion). There is one complete timeline for every possible series of universes configurations within the set of natural laws of its parent multiverse.