def build_account_collapsed_json(financing_json, registrations_json):
    """Organize account registrations as parent/child financing statement/change registrations."""
    for statement in financing_json:
        changes = []
        for registration in registrations_json:
            if statement['registrationNumber'] == registration['baseRegistrationNumber']:
                changes.append(registration)
        if changes:
            statement['changes'] = changes
    return financing_json