I have full custody of my two autistic grandchildren through the courts. My daughter (mother of the children) and the father of the boy have agreed to surrender their parental rights so I can adopt them (they are both mentally challenged and most likely will never get the children again). The father of the girl is unknown and I need to know if I will encounter any obstacles from the courts from trying to do this.

Yes, the court will require that you make a good faith effort to contact the father to get his permission.

You will need an attorney to prepare the paperwork, so that attorney can tell you what you need to do to try and get the father to relinquish his rights.