Confused about Voluntary Acknowledgment of Paternity (VAP)? It's a common way to establish paternity, often done right at the hospital. Here's what you need to know: 1 What Is VAP? It's Paternity means fatherhood. Establishing paternity gives your child a legal father. If you are not married and are going to need a paternity affidavit completed to add the father of the baby Paternity means fatherhood. Establishing paternity gives your child a legal father. If you are not married and are going to need a paternity affidavit completed to add the father of the baby Paternity Cases in Washington: Establishing Legal Rights and Responsibilities Family Law Attorney Robin J. Krane PLLC