I admit I do not have much experience with cats but maybe just once try opening a can of tuna when you get home at night - don't put much out that morning so she will be hungry and I wouldn't necessarialy put the whole can out (probably not good for them) but they can smell it a mile off. Put some on the food and keep the other cat away. Or just have the can out by you and see if she comes out to investigate... I think this is how some of the rescuers get their cats on this board. At least you might be able to see her and a little bit of tuna shouldn't hurt.. Debbie