Insp Gareth Evans of North Wales Police said: "We have had a number of incidents so I am asking members of the public to contact us if they see any persons who they feel may not be official workers".
Mr Justice Baker said that lesbian couples and their children had exactly the same legal status as any other parent and child, however "it is still open to the court, after considering all relevant factors, to grant leave to other persons to apply for (contact) orders".
The Missing Persons Bureau, based at Bramshill Police College in Hampshire, is the national and international point of contact for all missing people and unidentified body cases.