TWO DIFFERENT BIRTH CERTIFICATES; TWO DIFFERENT IDENTITY

Good Day! I'm a mother of two child. My first child is now 8 years old and my 2nd is 2 years old. Me and my ex partner didn't get married and we're already separated for almost 3 years now. I know his whereabouts but we can't communicate effectively, he's not visiting his children, and he's not giving support because he doesn't have a job. My eldest is using my surname and my second child is using her father's surname. It's very confusing for my children because they have different surnames. I know that my expartner will not agree to remove his surname from my child's birth certificate that is why I am planning to register again my second child in my surname and disregard the 1st one. But I will change "all" of the information that was written on her birth certificate including her name, birth place, time, year and I will just ask an attending physician who is personally known to me to sign the bc. I want to fix it asap before my child go to school.

I'm calling my child in a different name since me and my ex broke up, so she doesn't know yet her name that is written on her bc. I would like to register her in her known name.

My questions are as follows:
1. What are the problems that may arise in the future if I do this?
2. Is this considered as a fraud/illegal?
3. Will there be any conflict with the 1st birth certificate or other documents?

Thank you.

Kumonsulta sa abogado at idaan mo sa court ang surname change na yan.

Pa alala lang sa RA 8552, simulation of birth is a criminal act at syempre punishable by law once may naka alam at nagreklamo in the future.

Thank you for the advice. My child is illegitimate and she is in my custody. What if I file a petition for adoption? Is it necessary to have first the consent of my ex partner because his surname appears on the bc of my child? My child doesn't know him as her father because he's been absent for more than 2 years and he failed to support my child. He left when our child was just about 3 weeks old then. I need more advice please.

Thank you for your attention to this matter.

I think so, legitimate adoption (after you marry) can resolve that with consent from the bio father thru court and DSWD.