Dorthee Regine Pedersdatter in Aust-Agder

I am now at a stuck place with my paternal grandmother's mother. Thankfully I have a relative in Arendal able to help some. She had clarified that Gina Krøgenæs was born Dorthee Regine Pedersdatter. What a help THAT was! We then found her in the 1900 census, married to Lars Kristensen with daughter Petrine Marie Kristensen (disabled) living in Aust-Agder, Barbu 15 at the Krøgenæs farm: http://digitalarkivet.uib.no/cgi-win/webcens.exe?slag=visbase&sidenr=79&filnamn=f00990&gardpostnr=985&merk=985#c So now we know from the 1900 census: “Gina Krøgenæs”: Dorthee Regine Pedersdatter, and born in 1845 at Tromøen Ned married Lars Kristensen, who was born in 1837 at Øiestad's Ned I have found Lars Kristensen one generation back, 1865 census. But not his wife. I wonder where Tromøen Ned is? Is that in Arendal, Aust-Agder? I would like to find Dorthee in the 1865 census, or ANY information you think will help me find her antecedents. I also would love to find some more specific information on her children: Petrine Marie Kristensen b. 1872 (severely disabled)--death date? Helene Larsen b. 1874 (we know she married Hakon Sorensen, but was unmarried in 1900 census, contracted polio and died without children) Bertha b. 9 Apr 1877 one of twin girls (unknown married, name came to US) Gustava b. 9 Apr 1877 one of twin girls (resided in Arendal at Kroegenaes) Daniel b. 14 Jun 1879 (used Krogenass in US) Anna b. Feb. 1883 (on ship manifest as Kristiansen, married my Lars Hem) Martha b. abt. 1885/6 (unknown married name, came to US) Kristian Larsen Unknown DOB, married, 3 children in US, also died young, at sea This era of name changes makes for great difficulty! Berta/Bertha and Gustava and Gina all used Krøgenes or Krogenes at some point. I've found Bertha, Gustava, Martha, Daniel & his family & Gina on ship registers travelling to NY at Ellis Island. I'll keep searching, but sure would appreciate any help. Takk from Ellie in Tennessee