Grandma seeking advice

We have a complicated situation. My daughter became pregnant in high school (age 16) by a fellow student (age 17) and my daughter has raised that child as a single never-wed parent. My grandchild is now 5 (almost 6). Since the birth of my grandchild, my daughter has received one money order for $30 that we never cashed and still have - a week before my grandchild's first birthday. My grandchild has had not had ANY contact with the biological father since 13 months of age when he came into our house and beat my daughter up and gave my grandchild a black eye. (Local law enforcement was called but we were told that this was a "family situation" and that we had no proof that the sperm donor had ever really touched either my child or grandchild and that someone else hadn't caused those injuries!!) The biological father has conciously chosen to avoid any and all contact with my daughter and grandchild - kind of a smart choice for a month or two after the "incident". Now, my grandchild has NO CLUE who this person is. My question is...my daughter wants to terminate the biological father's rights to her child and name me and my husband (my daughter's biological father - married 29 years) as co-guardians. My daughter doesn't want child support. We have managed to make it without his help in the past and will continue to do so in the future. How do we make this happen? How do we get his rights terminated? He obviously has no interest in being a father! Does anyone know what we need to do? Our lawyer keeps telling us "don't rock the boat" and to keep waiting him out because the longer we wait, the better.