child's welfare

yung brother ko is in my uncle's custody since 3mo old. nagkaroon kasi sila ng papa ko ng verbal agreement na since wala pa anak uncle ko for 5 yrs of being married to her wife, sa kanila muna kapatid ko favoring my uncle's wish of experiencing having a child. but after a year nagkaanak sila, we waited for them to return my brother but they did not.we tried to talk to them nung 2 yrs old brother ko pero they want us to pay for 500,000.we cant provide that amount thats why my parents didnt continue having my brother back.now that my brother is already 9yrs old, and my parents are soon to migrate to other country, they are again trying to get my brother from my uncle but they dont want to give my brother back to us.we asked the dswd for advice and they only said that we should file complaint to the court for the case to undergo hearing. we consulted a public attorney and the lawyer made a letter a month ago inviting them for a forum with us for any possible settlement, but they didnt appear.
my parents seek help from police but they said they are hands-off in family problems.
we dont know what else should we do..
my brother is not adopted by them and there's no any single document signed by both parties regarding my father and uncle's agreement...