Kunz - Kowalkowski - Christburg/Marienwerder

Hello All
   
  I am seeking information on the family of Gustav Kunz born around 1875 in the Christburg area of Prussia - Gustav (and his wife, Jepe Olga Genff) had seven chrildren (4 sons: Max; Oscar; Franz; Gustav; and 3 daughters: Erica; Ella; Erna) between about 1899 and 1912...
   
  Gustav's son Gustav married Charlotte Kowalkowski and lived by the old Castle in Christburg, where he ran a coachbuilder's and car mechanics business bfore the 1939-44 war. These were my grandparents - Charlotte's family changed their name from Kowalkowski to Koll in the 1930's - she had 2 sisters (Elisabeth and Johanna) and three brothers (Hans, Paul & Bruno). She was born in Kurzebrack and her parents were Franz Kowlakowski and Anna Koschinski....
   
  Any connections out there?
   
  Peter Marsden