There are different ways to obtain target number one. The diameter of the wire itself can be increased or multiple wires in parallel could be used instead. Using multiple wires in parallel is nothing else than switching multiple DC resistances in parallel, which will result in a much lower over-all DCR. Now, by pointing out that multiple wires in parallel and in particular in a row can be used, it can be seen that there is still room between the wires to fulfill the winding window exactly. Instead of using a bunch of roundwires, a flatwire can be used. The outer dimensions, in this example of four roundwires or one flatwire, will be the same. However, by using a flatwire, the entire possible area can be used resulting in a much lower DCR.