[Mork]

We have 3 dogs at my house. Gizmo (a shih tzu poodle mix), Oreo (a poodle), and Mork (a Yorkshire Terrier). Gizmo is our male puppy and he is about a year and a half old. He's been marking his territory since we got him and that's usually not a problem as long as he is outside and marks the yard. However, with Mork here, it has become a problem. Unfortunately, Mork runs under him when he lifts his leg. He's, also, lifted his leg on Mork (and some of the other pets). How do we stop this?