I would like to find more information on John Gunderson Skjestadstuen and Pign Life Iversdatter Midun. I believe they are the unmarried father of Marthine. And Marthine may have a half sister. If they aren't married, then would her records be sealed? Is that why I can't find her? Any suggestions?

Pign Life Iversdatter Midun/Midtune died when Marthine was about five years old, but we aren't sure if she died in the US or Norway. Most likely the US. But I can't find any death information on her. I can't find anything on her at all except some records in the Gausdal church records, Oppland County =
Norway.In Digitalarkivet
Martine born Mai 7, 1870 to
Unmarried John Gunderson Skjeggstadstuen and pign(maiden) Life Iversdatter Midun.
there is a note that the father went to America.
In the 1865 census I find
Skjeggestuen- Ostre Gausdal, Oppland=20
John Gunderson, Unmarried, age 36
Ingeborg Gunderson Tjener ( houskeeper-kind of) age 34-Ungift = (unmarried)
His daughter- Ingeborg age 8
So- they were not married at this point- will look for marriage record , =
but he wasn't married in 1865 or 1870