This user showed up at my friend's minecraft home and demanded payment for the land (which was at least 10 diamonds and something else, I can't remember), saying that it was her land and accused her of taking down the sign. I had scouted out the area before I had given the coordinates to my friend and I didn't see a sign. After this, she reappeared at her door and when my friend asked if she needed anything, she responded with the fact she was allowed there. She has broken blocks in order to get into my friend's house, and although she replaced it so it couldn't be considered griefing, my friend no longer feels comfortable with her possessions in her house.