Biological Adoption

What is the name of your state? Viriginia

Okay, so my girlfriend is pregnant with my children, yes it's twins. She's stated that she wants them to have her last name after they are born. Now I would like to know if later in life I would have to adopt them for them to have my last name. And also since they wouldn't have my last name would I be left out of any legal rights I have with them?

If you wish to have a relationship with these kids, It would be best to start from birth. Once born, file for a DNA test to establish paternity, and if yours, shared custody. It is important to be in their lives as much as possible from the beginning. Were it I, I'd also petition to limit geographic area in which CP may move the children, because you two could break up some day, and without that, she could just pick up and move the twins cross country- you'd be paying CS for two kids you could hardly ever see.

You need not adopt them if the DNA is positive- you will then legally be the father. She will likely file for CS, so that will be handled as well. Once named, you will need either both parents approval or a court order to get their names changed.