no maiden name on birth ceriticate illegitimate child

Dear sir,

im planning to migrate to canada, and just confused for my application, because since childhood all my records/documents like diploma, sss id, NBI, bank accounts, land title, employment i used my mothers middle name. but i found out that on my birth certificate i had no middle name (blank). i already go to manila civil registry and they informed me that they cannot add my mothers maiden name on my birth certificate due to im illegitimate child...I would like to ask what can i do? is it possible that i consult a lawyer and make an affidavit that the person w/ and w/out middle name is only one? btw, only my passport,birth certificate and marriage contract has no middle name. please help me....thanks in advance