Depends where you live. In the UK, the person registering the birth can give any surname: http://www.legislation.gov.uk/uksi/1987/2088/regulation/9/made http:/

Depends where you live. In the UK, the person registering the birth can give any surname: http://www.legislation.gov.uk/uksi/1987/2088/regulation/9/made http://www.legislation.gov.uk/uksi/1987/2088/regulation/9/ma... In the UK, there is no legal formality around changing one's name (you can change it by deed poll if you want a piece of paper, but you change your name by simply using the new name), so they could change it themselves anyway whenever they feel like it.