The relationshps named in your post are a little hard to keep track of. I made the following tree that reflects what you said. Would help to have date of birth and place of birth for people - quite a few I couldn't find in the 1940 census.
Lars Petersen b Denmark [date?] Married Birthe Hansen [b when/where?] lived in Hill Creek/Herman, Washington County, Nebraska
CHILDREN 1. Hedvig (Hattie) Petersen married Herman Kjeldgaard A. Daniel Petersen m. Enola lived Brush, Colorado 2. Emma Petersen m Ed Olson A. Dagmar Olson m Kermit Goll - no children B. Ole Olson never married 3. Christina Petersen m Chris Kruse 4. Clara Petersen m Alfred Petersen A. Hubert Petersen m. Eulella - no info on children B. Arnold Petersen m Kathryn i Connie Petersen - twin i i Yvonne - twin C. Elna Petersen n Don Somebody - no children 5. Amanda Petersen m Niels Rasmussen A. Vernon B. Alvin 6. Thorvald Petersen m Julia A. Janice B. Phyllis C. Richard D. Darlene Possibly Violet