Inherited tenant signed lease after sellers agreement

[Rene Placido]

Hello All, I thought I’d give this a shot, first time posting on here. I recently signed and agreement to purchase a property the old landlord did not have any leases with the tenants as they were all family (property is a 4 unit) one tenant will be inherited and now has a lease with the old landlord for five yrs signed after I signed the sales contract that stated that I had to keep him there for one yr. is this valid? I live in Pa