I have 2 boys. Birth certificate has their dad’s name. We havn’t seen him for 5 years (youngest was 6 months old when he left).
Their official name is still their father’s but they were known by my name in nursery, they are known by my name at the doctors, the hospital, the dentist... everywhere except the bank.
When they started school, I had to fill out a form explaining the nam change and provide proof of permission. I couldn’t provide that proof since we had no contact. My solicitor and my ex’s former solicitor wrote letters backing up my version of events and supporting the known as name. The school had to sent the documents to the legal team at the local authority. The response was “you havn’t provided the proof we need, but given the circumstances we will approve the name change. If the father ever gets in touch to complain then permission will be revoked”.
So they are known by my name at school too.
I’m in Scotland, and it’s done on a case by case basis and the local authority agreed with me. The GP and dentist have never questioned it. Hospital appointment letters come through with my surname. It’s not an issue, obvisouly passport and bank will be the official name, but as soon as they are 16 they can change that legally.
It’s worth questioning it, but different councils will do things differently.