In NJ and fence separated your home from unkept wooded property for over 25 years Now land is being built on and part of your land is really theirs and vice-versa Can they make you move a fence that d?

First of all, definite ownership needs to be established. There needs to be someone who can locate the pins in the property and declare the exact property line. This can be a surveyor also. If you have built on their lot or they have built on yours, you can get the county government involved to make someone move it off your property.