Family Erickson research

I am doing research to find the great great grandparents of my husband who is grandson of Kristoffer Eriksen born 12 Feb 1843 Nes, Odalen, Akershus, who immigrated to New Zealand 1872 with wife Bertha Maria Olsdatter who tragically died on sea with their infant baby girl. I have the name Erik Olsen born 1802 Agotsrud, Sar-Odal, Norway -died 27 Dec 1869 Gjersoyenmyra, Sar-Odal, Norway, and wife name Ronnov Eriksdatter. Would like to find all the family members of Erik and Ronnov, children and their parents and grandparents names. I do appreciate any help I can get. Kind regards Christa Erickson