Para maayos ang birth certificate ng legitimated child, ayon sa website ng Philippine Statistics Authority, kailangan ninyong ipasa ang mga sumusunod sa local civil registrar kung saan nakaregister ang birth certificate niya:
a) Certificate of Marriage;
b) Certificate of Live Birth of the child;
c) Acknowledgement (not required for illegitimate children born on or after 3 August 1988);
d) Affidavit of legitimation executed by both parents which shall contain the following facts:
(1) the names of the parents;
(2) that at the time when child was conceived, the aforesaid parents could have contracted marriage, and that they subsequently contracted marriage,
(3) the date and place when such marriage was solemnized;
(4) the name of the officer who officiated the marriage;
(5) the city or municipality where such marriage was recorded;
(6) the name of the child to be legitimated, and the other facts of birth;
(7) the date and place where the birth of the child was registered; and
(8) the manner by which the child was acknowledged by the parents which may be in the child’s record of birth, in a will, a statement before a court of record, or in any authentic writing (not required for illegitimate children born on or after 3 August 1988).
Sa kaso ng legitimated child, ang kanyang original na family name ay hindi buburahin kundi maglalagay lamang sa remarks space na “Legitimated by Subsequent Marriage” at mayroong reference sa entry number sa Registrar of Legal Instruments. After ng proseso, legally ay pwede nang gamitin ng anak ang surname ng kanyang father.
Kung legitimated naman pero nais pa rin ninyong magamit at mailagay talaga sa birth certificate ang surname ng inyong father, pwede naman itong gawin sa pamamagitan ng pagfile ng Petition for Change of Name under Rule 103 ng Rules of Court dahil ayon sa Article 376 ng Civil Code “No person can change his name or surname without judicial authority.” Ibig pong sabihin nito, ang anumang pagbabago sa mga entries sa civil register ay kailangang magkaroon muna ng judicial order or utos mula sa korte bago ito mabago.