Zak and Zoey push each other to the ground all the time. Take a video of them would love to see if it is play. Maybe that was the advantage of an older puppy. Zak does not like to play frisbee with her, that was his game not her's.
They do this one thing out side that is so funny. They go out and do their potty on opposite sides of the yard then they do the long distance stare down, then Zoey run's and pounces like a cat onto Zak then the chase is on.
Lexi will get the hang of it when Enzo is bigger.