want to adopt cousins baby

My cousin is pregnant with 3rd child & does not want it. She wants me to raise & eventually adopt baby. My husband & I have two kids & wouldn't mind another. She said the baby's father is not involved & doesn't want the baby. My problem is what if his parents want the baby. What do I need to do. Can she sign baby over to me & how. I know it won't be legally mine till we adopt but is there paperwork we can fill out in the meantime.