Funnily enough they could, volksliste had 4 cathegories and actual German origins was not even necessarily needed. For example a enthusiastic nazi which lied a little could be easily signed to 1st or 2nd, someone married to a ethnic German to 3rd, and anyone really could be fit for a 4th as "racially valuable". Also don't forget that nazi racial policies were as inconsequential and malleable as needed.