I see. Thank you for clarifying that, Harry.
If there are not boundaries such as fences or other markers which have marked the boarders along the property for a period of years, the doctrine of adverse possession
would not typically aid you under these circumstances unless the owners of your property have been using the additional 50 feet as their property for a period of at least 7 years. If that is the case, then you could claim ownership of the 50 feet based on the doctrine of adverse possession.
Here is a link which discusses this legal doctrine:
If there have been no boundaries or use of the property continuously for a period of at least 7 years, then if you have no reason to dispute the results of the survey, the new boundaries would typically be set out where the surveyor has determined the boundaries should be.
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