Margaret's Neighbor

If Margaret has a neighbor, is it appropriate to refer to her as "Margaret's Neighbor?" Because that apostrophe would indicate that Margaret was in possession of her neighbor. Does Margaret really own her neighbor? Do you have a neighbor named Margaret? Do you only think you have a neighbor named Margaret? I would advise you to go knock on the door, and ask the person who answers the door if you can speak to Margaret. Because...I'm just telling you right now...

There is no Margaret.