Sounds to me like China Girl is really upset about the move. Cats generally do not like changes, and as they get older the dislike grows! A well trained Housecat does not "mistake" where her Cat Box is. She is telling you the best way she can that she is really, REALLY UPSET!
Try talking to her gently, and keep reasuring her that this move is for the best, that she will not be left behind, etc. When you get down close to them, and look them in the eyes and talk to them they do understand what you are saying through "mental images." Cats communicate with each other telepathicly through their thoughts. So, as you gently talk to her, visualize what you are saying in your own mind. China Girl will pick up on your mental images, so think very positive things about her and the impending move. She just needs your assurance that things are okay and that you will be with her. Remember, no matter how old your Cat gets, her mental age is about that of a Human five year old. I hope this helps you. Madame Joanne