Each co-owner may demand for a partition

Dear PAO,

Our family owns a vast tract of land which was being attended to by our former caretaker, Gilbert. Suddenly, we were surprised when he asked for its partition. He claimed that he is a co-owner of the land as evidenced by the certificate of title covering it. However, my father said that Gilbert cannot be considered a co-owner because he did not contribute to the purchase of the land. His name was merely included in the certificate of title because he was their caretaker. Does he have the right to demand a partition?