SIMULATION OF BIRTH

Five years ago, we adopted a one-month old baby by simulation of birth but we have contract agreement signed by both parents witnessed by the Barangay Captain that they are voluntarily giving the custody of the child to us.Both biological parents were of legal age at the time of adoption.(mother-20 years old; father - 21 years old) but they were unmarried and I believe they are separated now. Take note that the adoption did not go through legal process. Recently,the biological father is claiming custody threatening us that he will sue if we don't give up the child's custody to him.
Questions:
1. What court cases are we facing? And what are our chances on winning the case.
2. Will the contract agreement stand in court? (not notarized)
3. What are the possible counter-lawsuit?
4. Please advice.
Thank you very much.

simulation of birth is a crime. is there a birth certificate stating you are the parents? is so, you can be made liable if the charges are proven.

the biological father has no immediate right to custody because only the mother has parental authority over an illegitimate child. you can take the position that he has visitation rights, but you will only turn over the child to the mother who entrusted the child to you.

you can seek reimbursement of your expenses but you cannot hold the child as collateral.

custody cannot be a subject of agreement, much less parentage. any agreement may be void.