I think your biggest obstacle here is going to be the roommate/owner.
Training Zeus will be a breeze, training Ryan will be the hardest part.
It sounds like you are pretty much doing everything right, but without consistency it won't work. I know, I have that problem in my own house. When Zoee barks Bruce just yells for her to be quiet, instead of getting up to go see WHAT she is barking at.
Have you tried talking to Ryan about this? I have talked to Bruce countless times, I've just decided to deal with it my own way. But your issue is a bit more pressing. ((good luck))