How to prove filiation if you have no birth certificate and no DNA test done.

Legal Story Season 1 Ep. 2. Rodolfo, the supposedly sole compulsory heir is not being recognized by his relatives as the real son of his deceased mother Candelaria and his father. His filiation is challenged by his cousin who acted as the caregiver of Candelaria. This caregiver was entrusted with the land titles of Candelaria and claims not to know Rodolfo. The latter has no birth certificate and no DNA test done. Was his case hopeless?