You can apply to the Federal Contact Point as it receives applications from abroad when a parent living abroad wishes to re-establish or organize contacts with his child residing in Belgium. If there are no international regulations in place, the Federal Contact Point will refer you to other relevant stakeholders, such as the FPS Foreign Affairs. For more information and contact details: https://justice.belgium.be/en/themes_and_dossiers/enfants_et_jeunes/enlevement_international_denfants/contacts_avec_votre_enfant_a_letranger
All EU countries recognise that children have the right to a personal relationship and direct contact with both parents, even if the parents live in different countries. http://europa.eu/youreurope/citizens/family/children/parental-responsibility/index_en.htm
https://e-justice.europa.eu/content_parental_responsibility-302-be-en.do?clang=fr#toc_4