1 CHARACTER TYPO ERROR FOR MIDDLE NAME

Since I started schooling, I was using Logronio as my middle name, Now I am 36 and is currently working and found out 3-4 years ago that my NSO birth certificate indicates LAGRONIO as my middle name. Went to Manila City hall to check how I can correct the error since all of my siblings has LOGRONIO on their b.c.'s. But the requirements to change 1 letter is totally unacceptable. I was asked to get elementary school records of my mom which is impossible to get. Is there any other way I can correct it? Right now, I had my ID's changed following whats on my b.c. but it's still bothering me because i'm the only one who has typo error on my b.c. and I really wanted this fixed so I can apply for a passport.

They need evidence of your mother's actual last name before she married your father.

Her birth certificate should suffice.