I purchased some land a few years ago, based on the plat on file at the county courthouse. There is only one iron pin at one corner, the other boundaries are marked by treelines and creek centerlines. There are enough distances and headings on the plat to re-identify the corners. I came to find out that a neighbor who owns adjoining land set a steel pin ( maybe 20 years ago) which is at a location not indicated on the plat of my land. The location of the pin would indicate that my land area would be reduced by at least several acres compared to the plat. The neighbor said that the pin was set with the prior owner's permission.The land has only been used for timber during these years by PO of my land. I have title insurance, and want to have my land resurveyed. Would the PO have to have signed a deed or title transfer for the neighbor to have a legitimate claim to a portion of this land? What validity would any of these actions have if not filed at the courthouse? Any advice would be appreciated.