Your child's birth details need to be re-registered if you wish to add the natural father's details or if the parents have married each other since the birth.
You can download and print off the relevant form below or it can be obtained from the register office. Information on where to send the completed form to can be found on the form itself.
Apply to add the natural father's details on GOV.UK
Apply to add parents married since they initially registered the birth on GOV.UK
Where a father's details are added on a re-registration, he obtains parental responsibility. In certain circumstances, it may also be possible for two female parents to re-register following a civil partnership or marriage.