Where can I request the extracts and documents?

You can request an (international) extract from the Key Register of Persons (Basisregistratie Personen/BRP) of your child or yourself from the municipality where you live.

You can request an (international) birth certificate for your child from the municipality where your child was born.

You can request an extract from the custody register free of charge from the court. You can read more about this on the Judiciary's website (in Dutch).