Use and Enforcement: Easements

My question involves an easement in the state of: Pennsylvania

I am considering purchasing a property. This property and the property behind it used to be owned by the same family. The rear property is accessed by a driveway on the front property. there is no easement recorded. The property was divided into front and rear properties 29 years ago but the owners of the rear property have been there for about 4 years. If I purchase the front property, can I deny access to the owners of the rear property? I don't know if it has any impact or not, but the owners of the rear property are landlocked at that parcel, but they own, or their family owns, the adjoining empty parcel that could easily provide access to their property. We are not related to the people in the rear property and we are not on good terms. I am only considering this to increase my lot size because it adjoins my property on one side. There is a trailer on the front property but it will be torn down and possibly a garage built.

Thanks in advance.

Use and Enforcement: Easements