Well, based on the very high cost of living, its easy to end up spending 15000 a month.
I have a family with 1 child. I am thinking nursery / KG tuition at 3000, nanny = 2000, driver = 2000 (taxi). Then atleast 1 car = 2000, phone and other utilities = 1000, . All these add upto 10,000. I have not even included any food ' groceries and other household needs. Housing atleast another 10,000 (hopefully provided by employer). So, 15,000 for a family of 4 children is a possibility or may even exceed.