Question

Mr. Juan Dela Cruz and Ms. Maria Santos got married and started a family. They have a son named Mark. However, after a few years, Mr. Dela Cruz and Ms. Santos decided to legally separate and eventually got divorced. Mark, who was born during their marriage, wants to change his surname to his mother's maiden name, Santos. Can Mark change his surname to Santos? Discuss the applicable laws and legal procedures involved in changing surnames in the Philippines.