Legal Question in Family Law in Illinois

Absolutely. The designation on the birth certificate has nothing to do with your ability to collect child support from the real father. The real father, regardless of whether he is on the birth certificate, has the obligation to pay child support.

Yes, the birth certificate is irrelevant anyway. You will have to establish in court that the man is the father, and then set up child support which will be 20% of his net income. You can also get other items such as daycare and medical expenses paid by the father.