My son's birth certificate is blank where the fathers name is supposed to go because his biological father refused him. I have a protective order in place and our divorce decree mirrors the protective order stating he has no contact with either of us. I have re-married and my son wants his step dad listed on his birth certificate and to take his last name. Do I have to go through the process of terminating the biological fathers rights and having his step dad formally adopt him or can I simply add him to the birth certificate?

You will have to go through the formal process of termination of parental rights and then adoption. If your son is an adult, however, he can just have his last name legally changed.

Your state is important. There are requirements to be met governed by state law for termination of parental rights. Involuntary or voluntary. What state are you in?

https://www.wikihow.com/Terminate-a-Father%27s-Parental-Rights

We are in Texas.

Is this voluntary or involuntary? Read the provided "How to" link above in my previous post, it also contains requirement that must be met under Texas state law

https://www.childwelfare.gov/pubPDFs/groundtermin.pdf, about page 57, but fair warning there are forms that have to be filed in the proper court, and it's a LOT of work and they may not even have the forms you need.

Personally in Texas, you need a lawyer to guide you through the legal process, expensive and time consuming, to terminate this fellows rights, and have your child adopted. No you cannot just add the new guy to the birth certificate. I suggest you review the link I sent and set up a consultation with a FAMILY LAW attorney.

You can Google Family Law attorney's in your zip code, and get a fairly good list to go through, or get a list of legal aid attorneys near you, or visit your local courthouse, to see what you may be up against as far as forms, filing fees, times and dates. Then you can decide how best to proceed. I can tell you also my fellow Texan, many petition forms must meet a very strict FORMATTING criteria, and are available only to a licensed attorney, depending on the county and court.

The phone numbers and addresses of the courts are available on your COUNTY /City website.

Good LUCK

Were you married at the time the child was born ?