change of married man child's surname to a mother's surname

Good Day Atty.
My sis has problem. She had 3 yrs old daughter to a married man. The man and the wife still live happily. When my sis gave birth the man acknowledged the child in birth certificate. The man just visiting the child twice a week because he dont want to reveal his secret to his wife. When my sister asked him to choose between the wife and her, he chose his legal family. So they broke up and now my sister found a fiancee from USA. She want to bring the child together but the father not agree with it because he's jealous with the U.S man and he use the child as defense against my sis to remain in our country. What if the man really dont sign on the papers for allowing my sister to bring his child, does it have other option for that?
Does it really need his signature for taking away his child? What if we file in court to change the baby's last name, how long it takes? and does my sister can use his status as married man do get the chance to change the last name? Your reply is highly appreciated. Thank you so much

actually under philippine law, the mother has sole parental authority over the illegitimate child. Unfortunately, some foreign governments require some form of order from the court, and won't accept any certifications. One possible solution will be to file a petition in court to confirm the mother's right to custody and sole parental authority.

as for the last name, i find it doubtful that it can still be changed back. the revilla law allows the use of the father's last name, but says nothing about changing it back.

Thank you so much Atty.

hello again Atty. i just want to ask if how can i file a petition in court to confirm the mother's right to custody and sole parental authority about my situation? what evidence i can need? if ever i gained that right and sole parental authority to my child, do i have still the right to ask financial support from the father? thanks Atty.

you will have to retain a lawyer to assist you. you will need at least the birth certificate of the child.

Thanks Atty