A few days have passed now and I have Taz, Oreo and Rolls all running loose in the house, only Whisper is isolated. He might have a sinus infection of some sort, so I'm taking him to the vet on Wed. he'll be isolated until I can talk to the vet about him.
These cats are so nice with people, just a bunch of lovebugs. It took awhile for them to stop hissing and posturing, but no blood flew and everyone is settling down quite nicely now. Oreo is not a hisser, he just gives them plenty of room and stays in his own space.