My son has primary custody of his 4 year old daughter. Her mother is unreliable and irresponsible. She was given custody of her daughter every other weekend. She is not consistent in taking the child for her weekend. She was ordered to pay child support and has never paid a penney. My son has not made an issue of the child support. He is content with having his daughter with him the majority of the time, knowing she is safe while at home. My son and the child lives with me and my son's father. I help with the child, but we try to make my son the primary caretaker, etc. I am; however, no matter how you look at it, this child's female role model. My concern is what would happen if something were to happen to my son. Her mother cannot hold down a job and doesn't really have a permanent place to live. She has documented hospitalizations for mental health problems. Can a will be written to ensure that we as her grandparents would have at least primary custody of this child?