If your former spouse has become an unfit parent, you might be able to gain full custody of your children. You should document any instances of obvious negligence that occurred. An example could be leaving a child stranded at school when the parent was supposed to pick up the child.nIf one or more children complain of abusive treatment, you should write down the details. If one or more children return with bruises or injuries while in the other parent’s custody, that could be evidence of abuse and neglect.