Father purchased a property in 1993 through a notary and gifted to me

The seller has purchased the property in 1987 through a notary document from the owner and sold to my father in 1993 through a notary document. My father gifted the same property to me in 2014 though a registered gift deed. The first owner, second owner and my father are not alive now. The first owners family and relatives stay beside my property and making noise every day and claiming that the property is theirs's. Also, they are claiming that the first owners son not signed when sold the property and he has right to re-claim the sold property. Could you please advice, first owner son can claim the property after 30yrs? How can I protect my property and is there any documents I need to collect from authorities to protect my self?