There is no indication that Hjalmar worked at Spigerverk with his father and brothers. His occupation was a Postman according to the various censuses.
Hjalmar married Anna Maria Johansen. Their marriage produced four sons - Birger Henning, Ivar Flood, Trygve Bull, and Sverre Bang.
The children were left without a father when Hjalmar died in 1915. Through the following years, they had lost contact with the Bjerkmann side of their family.
Birger married and had 3 children. Ivar married, but it is unknown if they had any children. At the time of this post, it is unknown if Trygve or Sverre ever married or had any children.