Hello! I'm new to this subreddit, but figured it's the best place for some advice!

I'm the owner of a 5 year old JRT/Whippet. He is an amazing dog, but I'm worried he MIGHT have a problem with marking. For awhile, we lived in my own place, but he was still a puppy, and learning to not potty inside. We then moved in with my parents, who have their own 2 dogs.

My parents dogs are not very potty trained, and even though they have access to out doors, they would go inside, which would make my dog then mark over their scent. My dog, though, would NEVER potty in my room, ever. Even if my parents dogs did.

I then moved out into my own "apartment" (it's a glorified closet. 1 room, bathroom, and a "walk in" closet). Which he's only gone in twice. Once when he was sick, and once when he was way too excited. Other than that, never an issue.

But now I'm moving into a larger place, with a friend and her dog. I'm not sure what he's going to do, but if I had to guess, I'm 100% sure he won't go in my room, but the living room is what worries me.

What are the best steps to take to help prevent this? I work full time, so I can't watch him all the time, but I want to do whatever I can when I'm home.