The Olsen-Mellby siblings

I am looking for information on Marie Sofie Olsdatter, born jan25 1849, bap. feb. 18 1849 in Skjeberg, Norway. Her parents were: Ole Johnsen Melleby and wife Inger Henriette Eline Ingebretsdatter Marie Sofie was confirmated on sep. 25th 1864 in Skjeberg. She lived with her parents until she is listed on Aug. 1st 1884 to have emigrated to "America". (commen used for the USA, both also Canda I suppose.). I have not found her in the Digitalarchives, as this protocol for 1884 is not yet complete. And this is too early for Ellis Island. Marie Sofie had maybe two more siblings that emigrated. A sister and a brotther. They were: Anette Olsdatter Melleby, born Sep. 3rd 1851, bap. sep. 28 1851. (to same parents) She was confirmated on oct. 20th 1867. As she is not found in the 1875 census, I think it is possible that she emigrated some time betweenn her confirmation ( oct. 20th 1867) and December 1875. I have not found any indication other than a familyhistory that she could have emigrated. Also her brother Johannes Olsen Melleby, born dec. 11 1852, bap. jan. 16th 1853 ( to same parents. He was confirmated on oct. 18th 1868. As for Anette, he is not listed in the 1875-census So he must have emigrated between his confirmation and dec. 31st 1875. Melleby in the US has often became just Melby. Could anyone help me with any clues or leads on these three? As I only have an churchbookinscription on that Marie Sofie emigrated, I guess there is more hope to find her. Any censusfindings, immigrationrecords or anything else is most welcome, as always! Berta