
This is probably a title insurance issue. Find out if your Aunt received title insurance when she bought the property. Contact them and make a claim and they will pursue the matter on her behalf to help clear the title. Based on your facts, the neighbors has what's called " of title" to your Aunt's 50% of the pond. If that is not corrected, then after 7 years the neighbor could file for Adverse Possession of her share. This is probably an easy fix and just an honest mistake by the attorney that closed the neighbors sale, but it is better to take care of it now while you can.