<Snipped quote by UltikanaRe>
In most cases a last name and family house name were separate things. In both French and German case with house names that have prefixes "zu", "von" or "de", these are not the surnames of family members. They simply mean from where their house comes from or which area they rule. For example, the person who founded my family house was a knight by the name Karl Schultz and he was granted a fief - a small village or Rastenburg. So when his house was founded his name literally meant "Karl of Rastenburg".
Even though the head of the house may have moved on to a different location (e.g I've become duke of Manburg), most houses didn't change the name accordingly because certain family names hold weight and are well renowned. Habsburgs are a prime example. French house of Valois hails from the old medieval region in northern France called Valois, hence the name. :)
If your family was French nobility before coming to Austria then their family name would still be French, e.g "de Fleurs" would simply mean you are from a town/castle/village of Fleurs (probably doesn't exist but it doesn't really matter) and could keep it despite owning land in Manburg.
I know that, but I mean my house should really be de/von Dobersburg instead of Fleurs, as that is the land I now have. Similarly to how you were Karl Schlutz, then Karl von Rastenburg because you inherited Rastenburg. Granted, even though you cahnged a bit, I would have de Paris or something, meaning that it actually existed. In any case I would like to edit my house name, as I had just thought of it as a fairly random last name before reading this. Either that or changing the County names, whhich I would assume would not be a good thing. If you would accept this, I will go with the title Günther von Drosendorf, as I planned to have it so that I was a disinherited son of a noble, who was sent to Manburg to become a knight, who was then given a fief and became Herr von Drosendorf. Note that I am flipping the story from what I would have done with French homeland to Austria, this is mostly because I felt like it but I could maintain de Fleurs or something French if the general issue here was solved. then, as Herr of Drosendorf, which became even more powerful and became a good name, I helped in the formation of the Duchy. Now as far as the issue of retaining the birth name, being that I was a fairly removed part of a lower noble house, who sent me away anyhow, it makes less sense that I would retain that name..
I know that is probably pretty complicated, but I think it makes sense. Does it?