The 1865 Norwegian census indicates the family living in Hurdal in Akershus on the Tangen farm.http://www.rhd.uit.no/ftsoek/ftsoek.asp?kommando=bosted&...
Halvor was born in Gran - one of the parishes in the area of Oppland sometimes called Hadeland.
The 1865 census also shows a Hurdal farm or two by the name "Bratlein" and a middle aged man with the patronymic of Jonasson - possibly a brother to Kjerstine?
Look for parish records and/or written history books for Hurdal to accurately research the family lines earlier. (There is no bygdebok for Gran in Oppland but the church records do survive on LDS microfilm.)
Good advice at -http://homepages.rootsweb.com/~norway/articles.html