How to find child gridview in user defined function

Question

I have developed an application where I will have 2 gridviews one is parent and the other is child which is an Item template to parent. I would like to find the child control in a function of my own but I am unable to get can any one help me.

This is my code

private void Save()
{
GridView gv = (GridView)gvCustomers.FindControl("gvOrders"); // I am unable to get the child grid here .. Is it correct way of finding or is there any other way
}