Hello,There is quite a bit of information on Ancestry.com about the Westerkamp and Bruening families.
Christian Westerkamp - born 1855, 1920 Census shows that he was from Hanover Germany - attached census record. Some census records show his first name to be Christoph.
Katherina/Katerina/Catherine Bruening - Jan 26, 1856 - also from Hanover. Her parents are Adolf Bruening and Louise Rothert. Catherine's brother - George lived next to her and the Westerkamps from 1900-1930. I have attached his marriage certificate which shows the name of their parents.
Their son - Henry Herman Westerkamp - born Dec. 9, 1886 in a small town near Osnabruck. I have attached his Petition for US Naturalization, which indicates his place of birth.
I hope this helps in your search for the Westerkamp family.
Pat Wilke