Dear Bright Baby,
According to the Civil Code of the Philippines, a child who was born before marriage of parents can use the father’s surname as long as acknowledgement was made. This means that if your Daddy signed your birth certificate or issued an acknowledgement letter, you are allowed to use his surname.
If not, then you will use Mommy’s surname and you will leave your middle name blank. However, your Daddy can still file to acknowledge you by going to the Local Civil Registrar where your record is filed. Daddy will present an acknowledgement letter and other necessary documents so that you can use his surname.