you have added all the view to your scroll so,enumerate UIView from scrollview and add your anotherSubview to your UIView
for(UIView *myView in scrollview.subviews)
{
//Create UIView
UIView *anotherSubView=[UIView alloc]initWithFrame:CGRectMake(0,0,20,20)];
[myView addSubview:anotherSubview];
}