Paternity Tests and Birth Certificates

I have had full parenting rights of my now seven year old daughter since she was 2. Her mother has not seen her since and is now in prison til 2016. She told me she wasn’t mine before I got custody but a paternity test was never done and the possibility does exist. I’m worried that when released from prison she will file for test. What are my rights as far as custody or adoption go if proven she is not my daughter. I am listed as the father on her birth certificate