How to add father to birth certificate in illinois?

To add a father's name to a birth certificate in Illinois, you generally need to complete a "Parentage" form and submit it to the Illinois Department of Public Health or the local vital records office. Both parents must sign the form, and if the parents are not married, additional documentation may be required. There may also be a fee for processing the amendment. It’s advisable to check with the local vital records office for specific requirements and forms.