Map of Hannover c. 1877

Neither of the communities have changed their name, however the Scharmbeck is
presently referred to as Osterholz-Scharmbeck, they were seperate communities
until 1650. It is located 24km north of Bremen. The community of Überhamm is
located about 8km east of Osterholz-Scharmbeck, a very small community.
There is another Scharmbeck located near Winsen, south of Hamburg, but since
you referred to the two communities together, it is unlikely that the other
Scharmbeck is the one you are searching.
Source: ADAC Maxiatlas Deutschland
            Lexikon der Deutschen Städte
Hope this helps
Guenter in Michigan