Because Darwin will relentlessly chase Chocolate, (the same situation you have), the feline behaviorist suggested putting bells on his collar so she can hear him coming. It works great. However, when he's being a real stinker, he'll jingle his collar just to bug her. You might give it a try.Montressor will go to the door now and meow to be let out. I put a harness on him though, and he crawls on his belly. Today was putting it on him without the leash to walk around the house, and I wanted to verify the fit.
The bad news is he was so fearful with it on that he and Midway got into it (prey action/prey drive). The good news is that once we managed to move past the squabble Montressor seems to be adapting to the harness. I figure I'll keep it on them both for the rest of the day and put it on tomorrow as well.
We use Beastie Bands collars. They're made out of wetsuit material and common great colors and patterns. I found mine at Cool Cat Gear, but you can see all the patterns available by going to the Beastie Bands website. Cool Cat Gear will try to get you what you want if they don't have it. The collars stay on well but have enough give to allow a trapped cat to escape.