My partner's daughter has always had his surname, but lately keeps calling herself by her mum's surname. We've asked her and she says this is now her name but obviously she's too young for us to keep questioning her. Partner isn't on great talking terms with his ex so isn't something he wants to discuss with her YET. were just wondering is there a way we can find out what her official name is? Could the ex have changed this without him knowing? Does this affect CMS that he pays? He is on the birth certificate, or was at least. Thanks!