The original poster's description is a bit ambiguous so I know why you suggested what you did.
What the OP wants (as I interpret it) is for a circle to be attached to the vertex of the rectangle. e.g. if you have 1-inch square anchored at 0,0 and a circle anchored at 1,0 (the lower right corner of the rectangle) then when you resize the rectangle to 2 inches by 1 inch---keeping the origin at 0,0---the circle would automatically move to 2,0.
If you need that sort of functionality then other software are for you.