A: By law, parents have the preferential right over the custody and supervision of their minor children. The legal recourse is to file a petition in court asking for your appointment as guardian of the minor and the estate of your deceased daughter since the husband is unsuitable to discharge his parental duties to the detriment of the minor. The law allows the grandmother to exercise substitute parental authority. It is expected that your son-in law will contest the petition long and hard but for as long as you can convince the court the potential damage that he can inflict to the future of the minor, the law will be on your side.