If you are a member of the UK Family Visa of the worker should, in principle, be provided with a passport or identity card. For younger children who can not hold a single document, the laws of the Member States usually provide for the issuance of special identity or inclusion of a mention in the passport of a parent. It is not a national of a Member State of the Union, or should know that Member States wishing to travel to or through which you want to travel, may, depending on their nationality, require an entry visa. (see “List of countries subject to visa requirements).