We talk about the German people today and whether it is connected by common ancestry or not. There are no Ruhrpolen today from that time. If they have mixed with local Germans their German descendants have part in the same common German ties. And if a Pole comes today to the Ruhr area, it's no German and thus not of this topic.
You are making these overview-like and general discussions more complicated than they are. Precaustionary: Pls do not ask what is if there still is one individual left that has Ruhrpolen ancestry only.

