Legal Question in Real Estate Law in Maryland

Re: Tax Map shows my property belonging to someone else

You need to have a professional title abstrator do a title search in the land records. At some point there should be a "metes and bounds" description of the boundary lines. It may be that over the years a new deed was done inaccurately or incompletely. If you're able to get a good description, you can hire a surveyor to do a survey following the legal description. If you can establish that you own the land on which the family home sits, you may have a title insurance claim if there is appropriate coverage; if not, you might have to negotiate or litigate with the other claimant.