Family Code in the Philippines

Hi everyone,

Good day!

I have few questions and need legal advice to those who experienced and have knowledge about family legal issues regarding the visitation rights of my parents for the son of my late sister.

(1) My three year old nephew is born to an unmarried parents. Is the child considered as legitimate child? He is using the father's surname and as written on his birth certificate as well. My late sister and the father of the child lived together for almost two years.

(2) When my sister died during typhoon Yolanda my parents took the child home but the father asked my parents not to take the child while on the moving on process and they agreed. On the first five months everything was fine. The child comes to our home every month until last month when my father received a text message from the father of the child saying that at the moment he can not allow my nephew to visit his maternal side until he reaches his legal age. Can my parents demand for a visitation rights over their grandchild?

(3) I have read an article regarding family code. How true that if my nephew is considered illegitimate in case the mother dies, the parental authority will be on the maternal's parents? Is this correct?

(4) The father of the child is still under the assistance of his parents. No work yet and helps on their eatery business. If the father of the child did not agree to have an amicable settlement over this matter and if the child is illegitimate, can I adopt the child? We want him to be legitimate. I am married, on legal age. Me and my husband have a job and it is just fine with him if we are going to adopt my nephew since we do not have a child yet and we really love my nephew. That is why it is hard for us not to see him.

I hope you can enlighten me on this as the father is firm not to let the child visit my parents.
Thank you.