exparte evidence burden of proof on birth certificate

sir/madam, in an exparte evidence stage of divorce, the petitioner gives his proof of affidavit where the second marriage by wife and begot of child by her second marriage which is invalid but the ground for divorce based on adultery where outside of marriage she begot a child through her second marriage man while first marriage is subsisting. Here the petitioner points is not to punish and prove bigamy of her wife since burden of proof of her second marriage is on her to prove but the petitioner wants his relief on divorce on ground of adultery where a child was born to her and its birth certificate was available public. Now the petitioner question is whether just filing the birth certificate is enough or to call the registrar of birth certificate to prove the adultery ground in his exparte evidence? Kindly reply since petitioner lost his enitre livelihood on date of a marriage which was not consummated by petitioner. only on legally marriage between and his left wife was existing.