ActionScript 3 :: Flex - Get Object Which Own Property

My problem is to find out the object which owned my property... for example:
My Class :
public class MyClass{
var myGroup:Group; //Spark Component
.....
}

Now, I add my Group to another UIComponent. Next step in Class XYZ I wan't to get my MyClass Object ... but I can only see the var myGroup
public class XYZ {
...
public function getObject(group:Group):MyClass {
return group.????;
}
...
}