Bertha Olava Johnsdatter (Johnson)

Bertha was the daughter of John Thorsen Ullenes (b. 4-09-1817). He lived on the Island of Rennesoy, Rogaland. John first married Bertha Asbjornsdatter (14--04-1840) with whom he had Thore (24-09-1839); Asbjorn (14-02-1842); Andreas ( 29--07-1845); and Gabriel (10-11-1849). Bertha died 12-08-1853. John subsequently married Eliane Olsdatter (17-07-1857). They had Ole Johan (28-09-1857);Bertha Olava (6-o9-1859); Elen Johanne (1312-1862); and Theodor (10-10-1866). Thore & Asbjorn emigrated to the U.S. in 1865. Gabriel followed his brothers in 1870. Bertha emigrated in 1879. So far as I know Andreas, her stepbrother, as well as her brothers Ole and Theodor and her sister Elen Johanne stayed in Norway. The last record I have found is in the bygdebok by Lindanger and Waula. Ole is shown as a seaman married to Rakel Karine Gullaksdatter, Skjold. They lived in Lundsjoen in Hundvag. Elen Johanna is shown as married to Torson, Stavanger. Theodor is shown as married to Elen Gunhild Larsdatter, Naerland, Finnoy. He is described as a storekeeper or tradesmand and fisherman (?). He and is wife had a son, Lars Johan (31-10-18910 who drowned in 1912. I would like to see if I can trace any descendants of Ole, Elen Johanna or Theodor. I would appreciate any advice on the best way to proceed with this search.