Look at the lot and subdivision As far as I know, they don't use GPS to designate real property
I had a similar situation.. I hope you didn't pay a lot for your parcel. In my case the lot was a strip adjoining my land that had been dedicated 70 years ago for a private drive to access several lots behind mine built on 65 years ago.The county would routinely sell this strip for back taxes (its not even on my tax bill) and unsuspecting buyers would find out;
1 The parcel isn't big enough to develop
2 The parcel was dedicated as a drive (can't be changed)
As for your parcel under a structure I would think a survey would be required and then see the rules on adverse possession in your locale, because that is what someone might claim against your potential claim. I would be interested in hearing how this one turns out, if its a mobile park and they haven't been there 7 years it might be worth looking into.
Make sure next time you know what you are buying. The profit you are looking for may be a lesson for you and other BIGGER POCKET users.
so how long have they been on this property. this would help you understand if any claims have been made or if they even could be made
also is what is there even able to be developed
I would deal with this right away. There is something called "adverse possession" basically it means if someone takes possession of property, after a period of time they can claim ownership of the property. This takes 20 years in MD but many states have a shorter time frame.
I would talk to an attorney to see what my rights were and how to proceed.