villagers are never voided. You can prevent it by not loading your save file after it's been passed the moving day. You can TT to the moving day, and the villager would be back in boxes. As long as you haven't loaded your save file where she's gone.
So basically, you can have the villager in boxes, go on a vacation, and it will be like a week ahead of time. Just TT back to the moving day and she will still be in boxes.