Mandy,

I have checked my 20000-Austrian-locations list - nothing there, if the correct spelling is something like Bruderau or Bruederau. So at least it's not an official place name (or subdivision of a town) in present day's Austria.

However, if you search the web (google.com) you can find (1) a 'Bruderau' near 'Baumgartenberg' which is a small town in the Southeast of the province of Upper-Austria, near the town of Saxen, North of the Danube river. Not too far from CZ or Germany, but probably more than 50 kilometers from Passau.

Mapquest http://www.mapquest.com/ also shows a place in Northern Styria, near Liezen. This too, like the first one, seems to be a geographic name indicating something like a floodplain (which is the meaning of -au).

Hope this is of some helpf for your research

Tilman