Ragnhild Andersdotter Bjørkerud family

An acquaintance asked for help in finding ancestors in Norway before the family members immigrated to the US. He writes: "I would like to ask for assistance with Ragnhild Andersdatter Bjorkerud, b 1750 who m. Helge Nilson Jellum in 1774. She d. in 1810 in Jellum, Eggedal. I am interested in learning more about her mother, Guri Olsdtr Bjorkerud, b 1720, d. 1754 Bjorkrud. Is it possible to learn who Guri’s parents were?" I have found Ragnhild and Helge and family in the 1801 census http://digitalarkivet.arkivverket.no/ft/person/pf01058273003919 But I have searched the church records for Sigdal, Buskerud, without success. The records from the mid 1700s for Sigdal/Eggedal seem to be organized chronologically, but I have found only a few christening records for girls. Link to church records: http://www.arkivverket.no/URN:kb_read?ls=1&idx_id=8501 Does anyone have experience with the Sigdal records for this period and know where the girls are listed?