Moosmom- I didn't know you were having such problems with the new cat. Has there been any change? I hate to add to your stress level to keep suggesting other things...and you know when you have done all you can...but I have had some luck with the spray Feliway. It makes everyone smell the same, hence lowers the strange odor problem. Like JLB, I would do the one cat at a time introduction. It does sound like the new cat is attacking out of fear.

Keep us posted, and I am sorry it is so hard for you.