What Rights Does the Father Have

My question involves child support in the State of: South Carolina
My sister had a brief relationship with a guy and she got pregnant. The father wanted an abortion and till this day could care less for the child who is now 5 months old. My sister is scared to send in the child support papers. She already knows he wants nothing to do with this baby, but she is nervous that he may retaliate later on and want to be in the kids life. My question is, if she were to file for child support, what are the rights of the father in terms of having custody/getting custody of the baby later on. Is there any way she can file for sole custody, but he still has to pay child support. By the way, this guy is a serial baby maker and has 3 previous kids already, whom he does not pay anything to. Thanks for any advice...

Dad can file to establish paternity (if that hasn't been done already) at any time and request some sort of custody and an enforceable visitation plan.

Sole custody would not mean that Dad couldn't ever see the child.