Certificate of title best proof of land ownership

Dear PAO,

My godmother is the only child of her deceased parents. She went back to her parents’ hometown because she wanted to restore the property, which she claims belong to her parents who bought it sometime in the 1970s. However, she was surprised to learn that the property was titled under another person’s name. Since the property is already fenced, she could not enter it. In fact, she was prohibited from entering after she asked assistance from the barangay (village) government. She has a copy of the contract relating to the sale between her parents and the person from whom it was bought. Does it have no value in proving that their family is the owner of the property?