My Girlfriend Sees People That I Can't See

I met my Girlfriend Amy about 4 years ago and soon after we became a couple she moved into an apartment. Well after awhile Amy told me that she sees someone in her closet. I of course didn't know what the heck she was talking about so I had her explain to me. She said that there was a guy that would poke his head out and look around and stare at her. She said he was kind of strange looking and described him to be dressed like a thug from the 50's of 60's and he had a smile like the joker from batman. Amy said that he never came out because she told him that he had to stay in there but she said that she could sense that the guy in the closet did not like me at all. Well nothing ever happened and after talking to her more she told me that seeing things happens a lot but she has no idea what to do with this. So fast forward to now, we now live together in a house in a different neighborhood, and it took about a month but then Amy started to see a whole bunch of different people just wandering around inside our house. She said that the staircase going upstairs is the most busy and there are always people there getting in the way and just generally being annoying and sometimes trying to "jump scare" her. So they obviously can see and acknowledge her. I mean she sees people standing even on our kitchen table and she sees them peeking out of our basement door as well. I forgot to say that she just found out that she is an Empath, i'm sure that has to have something to do with it. So she came home last night and Mr "Joker grin" was back after almost 2 years and he was just laying on our living room couch when Amy walked in from the garage. Amy is still obviously trying to learn how to deal with the Empath stuff, even tho she is super glad to have been able to find out what was causing all the now known Empath traits that she had going on. But we were sitting together watching TV last night and she just gets up and pushes the basement door closed, so I ask her "what's up?" and she said that someone was "peeking". So this stuff does freak me out a bit but I went to bed shortly after that and then this morning she told me that things got kind of weird after I went upstairs. She said that she was sitting there still watching TV with both of our cats sitting with her on the couch when the basement door just pushed itself open again. Well that kind of scared her so she yelled at who ever it was to leave and then she sprinkled salt in front of our bedroom door. She said it felt like the "joker grin" guy again but after she did that she didn't have anymore issues during the night. I really kind of think that our cats can see whatever it is she is seeing as well. We are getting ready to move to a new house that we just bought and we already have two great big bundles of sage and a bunch of salt. We have been in our new house a couple times and she hasn't seen or felt anyone in there. Anyone else have weird stuff like this happen to them and any other or better ideas on how to make sure they stay out of our new place?