What you are describing is clearly a delusion. If you saw a love one in your home, when they didn't live with you or anything, you would not have a normal conversation with them. There is simply no way. If I get up in the morning and go into the kitchen to have breakfast and my mother is sitting there and I just start chatting with her, then there is something seriously wrong with my thinking. The fact that you accept that they are there with you so willingly is in it self a delusion. If you were in a normal state of mind you would clearly ask them what are they doing there, how did they get there, when did they arrive.

If you are suffering from these types of delusions, there is no way you would even realize it. The person who saw there recently dead relative could have seen other people as well and wouldn't have given it a second thought. They could of seen Obama in their living room and had a friendly chat with him and would of accepted it as real and no one would ever know. They wouldn't think it is odd at all. Then after Obama left their relative arrived and they spoke with them too.

A person suffering from a delusional state is clearly a bad witness for anything. If you are incapable of telling reality from something entirely in your head, how can you give an accurate account of what happened?