Thanks, this example works exactly how I asked.
I also have more complicated scenario and wondering how this code would translate to it. I'll use a similar analogy.
Imagine a person walking a dog. The person has a free range of motion and is controlled with 8way direction and can go anywhere. The dog also can be controlled with 8way direction (like a two player game) but is limited by how far it can move away from the person because of the leash.
So basically how to 'tether' a moving object to another moving object?