My cousin is having a baby and doesn't know who the father is. We live in Illinois and she wants me and my boyfriend to just sign the birth certificate. Is this possible for me and him to just sign as if we were the parents?
This is both not possible and illegal. The hospital will most definitely not allow you to sign the birth certificate. This must be signed by the mother, and the hospital will make sure that only the mother signs the birth certificate.
If your boyfriend signed as the father, this is fraud, and a very serious crime. In addition, there are serious ethical and moral implications. The child needs to know who their biological birthparents are for medical reasons. Finally, the child is likely to be devastated when they find out that the information on the birth certificate is fake.
An adoption is possible, if the birthmother wants to relinquish her parental rights, but all of you would need to work with an adoption agency or adoption attorney who can work in the state of Illinois (IAC cannot). You would need to go through a home study process to determine that your home is a safe emotional and physical space for a child. The home study process includes a criminal background check. Unfortunately, this process will cost between $10,000 to $30,000 depending on who you work with.