This is not my own theory it is one i came accross and that i thought was a good one:
Let me preface this by saying I don't think this will happen in book 7!
But, let's just say for arguments sake that Harry found relics and thought them to be Voldemort's horcruxes.
Could he bring them back to Hogwarts, open the Maurder's Map and since living soul would be in these relics, would they register on the map as Tom Riddle?
Fred and George had the map when the Diary was in Hogwarts in CoS, so we don't know how often they looked at the map and if they would have even noticed or cared about someone named Tom Riddle (as not many people ever knew he became the man known as Voldemort).
They were probably more interested in avoiding teachers and sneaking through the passages.
So that begs the question, if Harry was to bring a horcrux back to Hogwarts, would it register on the Maurder's Map?