The zakah of orphans' wealth in the hands of the guardian

Question:
I am the guardian of orphans and a widow, and I have collected money for them from their father's pension for ten years or more. After that period, I had about three hundred and fifty thousand riyals in my possession, so I bought them a small apartment and they moved in. During that long period of collecting the money, I did not pay the zakah, and it has now become apparent from my liability. The question is: Am I required to pay the zakah for that long period? I do not know the exact years or the amount for each year, so how should I proceed? May Allah grant you success.

Answer:
The zakah is upon them, the owners. Inform them that you did not pay the zakah. You are their representative. The zakah is paid from the wealth itself. They are the owners of the wealth, and the zakah is due to them from you. The zakah is upon the owners of the wealth. So, inform them that their wealth requires such and such an amount of zakah for such and such number of years, and they will pay it.