I think what you are doing already sounds good. I put Nebo on a leash sometimes when he's trying to play with Reggie/Smokey. I know that I couldn't face getting rid of Nebo, and I don't think you should get rid of Chewy. I think I would just watch him at all times, and definitely not let them be alone together. Chewy is not trying to hurt Teddy, but Teddy probably thinks he is fighting with him and is trying to protect himself. I'm betting with Chewy and Nebo...once they get a bit older, they will calm down...and things will go better. How old is Chewy anyway? I think they are around the same age.