I am glad to see that you picked up some Rescue Remedy. With my 5 cats I wouldn't be without it. Hopefully the lady at the health food store pointed out different methods of using it on the cats, but just in case she didn't I will explain the different methods I've used, which I have found worked quite well. If you are using the alcohol base Rescue Remedy I have found that it is too hard to administer orally. If you are using eyedropper bottle I'll put a couple drops behind both ears, or a couple drops between the toes on the front feet. I have also put a few drops on the belly and rubbed it in. But the method I have found the best in a multi-household is to add it to the drinking water. I'll put 6 drops in the drinking water every time I change it and I usually change once a day. If you're using the fountain at 6 drops daily and don't forget to add the 6 drops when you change water in the fountain.
I would have to think that there is some stress between the other cats as well, and if it's mixed into the water and they are feeling the stress it will work on them as well, if they are not stressed it will have no affect. That's one of the nice things about Rescue Remedy you don't have to worry about overdosing with it. It might take you to a 3 days to see any results, and I think with Ginger I would be administering a little extra individually to her for the first day or 2 to hopefully bring down the stress level a little faster.
Rescue remedy won't work in every case but it's worth a try. I had a customer that had a cantankerous stallion they could not load in the trailer until after they had mixed it in the drinking water for the horse, and within a couple minutes of finishing the water they were able to lead the horse into the trailer.
I really hope this helps to relieve some of the stress for Ginger and you know you could take some of the Rescue Remedy to help relieve some of your stress as well. LOL
I don't know whether you have seen this website, it could be of interest.