If they have been paying rent or doing something on an exchange basis, I doubt there's an adverse possession issue. Plus, there's an acronym CANOE --- Continuous, Adverse, Notorious, Open, and Exclusive ... and that has to go on for years for each person. Has one of these gypsies really been there that long? How could they prove it? You could suggest to the new family member that he is losing a bundle by having these folks hanging out and he should be charging real rent and really collecting it. If they balk, call the cops ...