Paying Zakah for the previous years

Q 1: My grandmother is more than eighty years old. As she is no longer able to manage her worldly or religious affairs properly, my father, in agreement with other uncles, decided to open her safe where she saves her money and the like to ascertain how much money she has and pay the Zakah (obligatory charity) due on it from that which has reached the Nisab (the minimum amount on which Zakah is due), which was not paid for years. They found more than 20.000 Riyals. However, the problem that faces them is: how should they pay the Zakah due on this money, especially after the passage of several years during which the due Zakah was not paid. Please advise them how to pay the Zakah due on this money in the proper way. (Part No. 8; Page No. 332

A1: It is Wajib (obligatory) to refer the issue to the court so that the court would appoint one of your grandmother's sons as her deputy. After that he should pay the Zakah due for every year after the completion of the year. He should try his best to count how many years have passed and work according to what he thinks is most likely correct after consulting other brothers. He should pay the Zakah due on the years that they believe she did not pay the Zakah for them. May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.