Kopp; Mildner

Looking for family with last name Kopp or Mildner.
Both families were Sudeten Germans and came to Canada, arriving in St. Walburg, Saskatchewan in 1939.

Helge Auguste Mildner (on birth certificate or RODNY LIST her name was listed as Helga Augusta Anna Mildnerova) was born Dec 27, 1924. Her father is listed as Vilem Mildner (date below says 19.9.1902 Sternberk) and mother as Anna roz.Churawa (date below says 7.2.1904 Bratrusov).
Helge’s father was killed in a train accident and her mother remarried Franz Konig before coming to Canada.
Helge had two brothers who didn’t come to Canada – Wilhelm (Willy) who has passed but he and his family immigrated to Austrailia and don’t have any information; and Hubert whom we have never located.

Erwin Augustin Kopp (no birth certificate available) was born July 25, 1919. He and his brother Ernst and sister Margarete came to Canada with their mother and step-father George Frenzel. Family history goes that his father passed away in 1978 give or take a year or two. He apparently remarried and had another child, oral history indicates he too was from Sternberk although Helge and Erwin didn’t know each other before they left Czechoslovakia.

Erwin and Helge were killed by a drunk driver in September of 1982. They were my husbands’ parents and we have been trying to track down any relatives that may still be in Sternberk or in Czechoslovakia. Maybe someone has heard this story or a similiar one.
Any guidance would be appreciated.