Complex sentence: "Emerging varieties of Filipino which deviate from the grammatical properties of Tagalog" has been observed in Davao City and Cebu, which together with Metro Manila form the largest metropolitan areas in the Philippines.
Split into simpler sentences: Emerging varieties of Filipino which deviate from the grammatical properties of Tagalog has been observed in Davao City and Cebu. Together with Metro Manila, the three form the largest metropolitan areas in the Philippines.