We have a seasonal home on Summit Lake, NY. The property next to ours has no structure on it and the owner has not used it for about 7 years. We received permission from this owner to use his driveway and the property as long as we never used stakes on his property. We have only used the driveway and played games such as baseball and Frisbee on his property. This property owner has recently passed away (he does have living heirs). The property owner on the other side of his property has told us and other property owners that he is taking over the property and feels he can claim this property because he mowed the lawn for 7 years. He never lived on this property. From what I understand he has no paperwork that he bought the property and proof that he has legal rights to the property. Does he have the right to tell us not to use the property even though we had permission from the owner. He has also blocked the driveway with a camper. Can he do that?

Maybe. The principle here is called adverse possession. In NYS it is not easy to prove adverse possession and just mowing the property for 7 years is not enough. First the time limit in NYS is 10 years, secondly, there has to be more than just mowing.

You may actually have a greater right to the property since the owner granted you an easement during his lifetime.

I would consult a real estate attorney in the area. But I'm pretty sure the other neighbor is blowing smoke. And that an adverse possession claim would not be upheld. Also such a claim has to go through a court he can't just decide he has ownership.

The neighbor who's been mowing it has no case. He would have to show that he has been treating the property as his own in an "open and notorious" way for at least the last ten years - such as by paying the real estate taxes on it and taking steps to keep others off such as by fencing it, and/or insisting that you get his permission before using the driveway. Also if the owner was aware that this person was mowing the property and gave his permission to do so, that eliminates the neighbor's claim of adverse possession. If I were you I would contact the owner's next of kin and alert them that someone is trying to take land that rightfully belongs to the heirs.