In the past, before the war, Edith has worked as a maid and because of this know the secret passages in the house. Hans Geering has also previously worked at the Chateau, presumably for General Von Klinkerhoffen.
During the series Von Klinkerhoffen are using this site as a private living. Once Von Klingerhoffen announce the Chateau will be the operational center for german military operations in the area. Its also once revealed that Lt. Gruber have his private quarters, after he is acquired by Klingerhoffen to be his ADC.