Deployment issue, maybe speak with jag?

BD and I both military. He now doesn't want his baby, saying she isn't his. Okay dude, then ill get you for child support. He deploys a month before baby is due, hes lied to his chain of command that he is expecting a baby after I told them. how does getting a paternity test work if hes going to deploy before baby is due? His CO won't do anything so I know I'm going to have to serve him. Can there be a dna sample on file? What steps can i take??