It's always wise to seek professional advice when faced with possible legal action. We recommend contacting a real estate attorney for their input.
Since there was no written agreement between you and the family member, that member has no legal standing to sue you for anything. The family member is just upset. I find it hard to imagine an attorney agreeing to sue you for damages, if the family member actually contacts an attorney, as there is no proof of any agreement with the family member prior to your sale to someone else.
Best of luck to you. cj email@example.com