Hi,
The Norwegian church books and censuses are available fro fee use at http://www.digitalarkivet.no/cgi-win/WebFront.exe?slag=vis&a....
The Norwegian genealogy association DIS Norge also has a forum to place enquiries, http://www.disnorge.no/eng/index.html.

Information regarding genealogy research in Norway, http://www.rootsweb.ancestry.com/~wgnorway
Information regarding the Norwegian bygdebøker, http://www.rootsweb.ancestry.com/~wgnorway/NorLinks1b.htm
You might also want to have a look at information in the bygdebok of Dybvåg
Dybvåg gårds og slektshistorie, bind 1, published in 1965. By Daniel Danielsen og Sophus Jenssen.
Dybvåg gårds og slektshistorie, bind 2, published in 1965. By Daniel Danielsen og Sophus Jenssen.
Dybvåg gårds og slektshistorie, bind 3, published in 1965. By Daniel Danielsen og Sophus Jenssen.
I’m not sure about UK but in the US you can order these books via inter library loans. Try the library or try to find a volunteer to look up information for you.

Lyngør is in Dypvåg parish in Aust-Agder, today Lyngør is a part of Tvedestrand municipality,
The priest handwriting is difficult to read, I have looked through 1870-1874 but I didn’t find her, but I might have missed her.
However, I found her confirmation.
Dypvåg 1885-1906
http://www.arkivverket.no/URN:kb_read?idx_kildeid=981&id...
Confirmation 5th of September and 17th of October 1886
Fredrikke Wilhelmine Christoffersen, born 5th of October 1871, baptized 8th of December 1871, born and lives at Lyngøer
Parents Knud Bjørn Christofferesen and Louise Amalie
She did quite good, her grade is 1.5 (1 is best)

Well, then I found her baptism record
Dypvåg 1855-1872, no 118
http://www.arkivverket.no/URN:kb_read?idx_kildeid=789&id...
Frederikke Wilhemine
Parents: Knud Bjørn Kristoffersen, age 31 and Louise Amalin Kristoffersen, age 24
Address: Lyngør + a word I’m not able to read.

Knud Bjørn with his parents and siblings in the 1865 census of Dybvaag, they live at Lyngøer yttre,
http://digitalarkivet.no/cgi-win/webcens.exe?slag=visbase&am...

Here is an online Norwegian American dictionary: http://home.online.no/~otjoerge/files/word.htm

DIS Norge, cemeteries I Norway, Dypvåg:
http://www.disnorge.no/gravminner/vis.php?mode=pe&id=158...
These are all buried in the same grave:
Louise Amalie Christophersen, maiden name: Wiersen, born 29/8-1849, died 2/10-1894
Fredrikke W. Christophersen, born 25/10-1871, died 18/5-1930
Anders Marcussen, born 20/1-1806, died 26/4-1846
Karen Margrethe Marcussen, maiden name Christophersen, born 26/1-1811, died 18/6-1897
Karen Regine Christophersen, maiden name Wilhelmsen, born 20/10-1878, died 18/1-1956
Sam. Marcussen, born 9/6-1879, died 10/4-1960
Jens M. A. Marcussen, born 9/3-1837, died 25/1-1927
Anne Marie Marcussen, maiden name: Christophersen, born 2/8-1838, died 20/7-1889
Ingeborg Louise Marcussen, maiden name Pedersen, born 18/4-1873, died 22/11-1907
Ruth Marcussen, born 25/6-1882, died 12/4-1842
Sara Louise Marcussen, born 7/10-1872, died 1/2-1876
Anne Magdalene Marcussen, born 15/5-1865, died 20/7-1949
J. C. Marcussen, born 12/12-1839, died 9/10-1875
Edle Marcussen, maiden name Christophersen, born 17/7-1851, died 28/7-1940
Olga Fredvik,maiden name Beck, born 5/4-1877, died 28/12-1955
Anders M. Fredvik, born 6/7-1875, died 13/4-1964

This is most likely Knud Bjørn’s parents, all are buried in the same grave:
http://www.disnorge.no/gravminner/vis.php?id=1581&mode=p...
Chr. J. Christophersen, born 31/8-1805, died 26/4-1880
Anne Margrethe Christophersen, born 12/7-1812, Borøy, died 7/8-1867
Johannes Christophersen, born 28/12-1880, died 16/11-1975
Hilda Christophersen, maiden name: Nielsen, born 8/1-1888, died 27/8-1965

Dybvåg 1824-1840 (It’s difficult to read)
http://www.arkivverket.no/URN:kb_read?idx_kildeid=787&id...
Married 6/12-1832
Groom: Christopher Christophersen, age 28, Lyngøen
Bride: Anne Margrethe Christophersen, age 30, Borøen
Grooms father: Jens Christophersen
Brids father: Gunder Christophersen

This is most likely Knud Bjørn’s brother Jens Andreas and his family in the 1900 census of Dybvåg,
http://digitalarkivet.no/cgi-win/webcens.exe?slag=visbase&am...

Confirmation
Dybvåg 1872-1884
http://www.arkivverket.no/URN:kb_read?idx_kildeid=6154&i...
Confirmed 5/10-1884
Kristofer Kristofersen, born 5/8-1869, baptized 11/8-1869
Parents: Knud Bjørn Kristofersen and Lovise Amalie

Dybvåg 1885-1906
http://www.arkivverket.no/URN:kb_read?idx_kildeid=981&id...
Confirmed 13/10-1889
Anna Margrethe Kristoffersen, born 1/8-1874, baptized 22/9-1874
Parents: Knud Bjørn Kristoffersen and Louise Amalie

Dybvåg 1885-1906
http://www.arkivverket.no/URN:kb_read?idx_kildeid=981&id...
Confirmed 2/10-1892
Julie Kristophersen, born 28/12-1876, baptized 1/1-1878
Parents: Knud Bjørn Kristophersen
Dybvåg 1885-1906
http://www.arkivverket.no/URN:kb_read?idx_kildeid=981&id...
Confirmed: 13/10-1895
Johannes Kristoffersen, born 28/12-1880, baptized 9/5-1881
Parents: Knud Bjørn Kristoffersen and Louise Amalie

I have looked through the confirmation lists until 1904.
I have not been able to find Louis Amalie’s baptizm record or in the 1865 census

Regards,
Arna