Looking for a needle in a Heystack

Hello and many regards from Norway Between 1870 and 1890 my great grandfathers two sisters left for US. I belive the boat went from Kristiania / Oslo. Marith, born 1853/1854 and Petronelle, born two years later. Both was born in Dovre prestegjel in Lom Gudbrandsdalen. The husmansplass or main farm was called Sandum. Their parents name was Peder and Brid (Britt) Pedersen. They were born in 1816 and 1827. I dont know if the sisters left Norway together, if they was married or had kids. My gr. grandfathers name was Ole Pedersen Dahl, he was the youngest and born in 1863. He married and lived the rest of his life in Oestfold. He had 8 daughters and a son. I'm the sons grand doughter. I cant find any information abouth the sisters after 1865. The next info I have found just one daughter Joeda, lived at home. She was unmarried and born in 1850. There may have been more children in the family I wish this information fits into someones puzzle. I know there has been Americans in the village Lom loooking for relatives. Our family used the sirname Dahl. If anyone know something please contackt me.