Sverre Martinsen,or Ethal Woldseth

Sorry but I am new at this. I am trying to find family living in Norway. How strange is it that out of 4 grandparents they all came from Norway and found there sweethearts and Married in the U.S..Ok here is one of them my grandfather his name is Sverre Martinsen he was born in Trondheit Norway on Oct .4 1904. He came to the U.S. throw Canada in 1927.I only know of his sister's names and I am sorry for the spelling of there names My Aunt is old and she gave them to me. Olga, Constins, Dongane. and i think the last one sounds like Quear.his brothers names I don't know. He met my grandmother in brooklyn and married her in New York. Her maiden name is Ethal Woldseth and they had four children. My grandmother's family is from a small Island outside of Bergan call Crossa or OS. She has a brother Otto Willset again I am sorry for any miss spelling. I think her father's name was Jacob Crossa her mother's name was Martha she was married a couple of times her other marriage name were Thomson, Willset and Yohenson. Her mother's maiden name I think was Martha Hansen or Hanson. Can anyone help me. Thank you so much for reading Vivian