Whatever magic or other contrivance is in place in this city to draw us here to fight this battle, in addition to being capable of bringing people here from different worlds, can also access different points along the timeline of an individual plane of existence. Just as I've arrived here from a future in which I work under you once you've become the head of JP's, your sister has arrived from a point in time when she's old enough to be acting in an official capacity as well.