I am also researching the family of Elling/Eling Petersen/Peterson/Pettersen. I have just recently discovered the family members. My husband's grandfather was Ole Peterson, brother of Ingaborg. I know that Ingaborg Peterson married Arne Arneson on 8 Dec 1909 in Dallas, Barron County, WI. Inga and Arne had 7 children, Olga Geneva, Allis Irene, Amel, Emil, Helen Eleanor, Raymond, and Marvin. They lived at least part of their married life in Rice Lake, WI. She died in Rice Lake, WI on 4 Sep 1968. Her brother Einar Peterson settled in Rice Lake, WI and died there on February 4, 1979. She had a sister Petra Julia, who married Louis Louis on 6 Oct 1914, and who also lived in Barron County, WI. She was born 8 Jul 1886 and died 4 Sep 1970 in Rice Lake, WI. Most of the marriage and death information for Elling's family is recorded in the Barron County Register of Deeds office in Barron, WI.
I am interested to know the evidence you have for the Norwegian ancestry of Elling and Olava Peterson (as they spelled their names here in Barron County). Like I said, I have searched in vain for any information about Ole Peterson, only to find all these family members last week based on Ole's obit which appeared in the Rice Lake Chronotype in 1965. I would share all the info I have on the family, if you will share all you have from Norway and the source citations for the information. For instance, do you know who Elling Peterson's parents were, siblings, etc. and where they lived and died in Norway?
It's exciting to finally find out something about the family, since Ole's grandchildren know nothing about them, even though they all lived in the same county in WI. Ole's daughter Agnes was my husband's mother.