How to get divorce if the female partner is missing after getting caught for illegal affairs.

My aunt was having an affair with one of my another uncle in my family . Even before the my aunt was having an affair with another person and when she was caught our family and his husband that is my uncle had given her another chance. But this time she was caught having an affair with a person from the same family of ours. When thier illegal affair was disclosed in front of all family member she just left the house with her two daughters . And the guy she was having illegal affair committed suicide . So at present this no one knows where this women is living . Her daughters are with their maternal grandmother and are not willing to stay with his father just cause the feel shame to stay in that area where all this thing happened . THE POINT is my uncle wants to get divorce with her wife but his wife has flewn somewhere because of the suicide case . MY uncle wants to marry another women as there is no one in the house with him to take care of. So we need suggestion regarding how can we get him divorce with that women. Our main motto is to get the uncle Talaaq and make him free .