I have never heard of the Feliway collar. I am not sure if Trouble is going to be aggressive with Floyd or not. That is the part I am a bit confused about. I have never seen two male cats, one intact and one neutered that didn't even so much as hiss at one another. Especially when the neutered one has a history of being aggressive/assertive. Now of course both are neutered. I am wondering if you all think Floyd is being super submissive in his refusal to look at the other cats and if that is going to be a problem? Also, what do you make of Trouble and his non-aggression at least through the cage with Floyd. The females have all hissed and snarled at Floyd but Trouble just looks at him like he wants to play.