Othelie Olsen Rønne and Margot Olsen Rønne

I am trying to help a friend/relative through marriage, solve the puzzle of her great-grandmother, Othelie Marie Olsen Rønne, and grandmother, Margot Olsen Rønne. Margot was born 30 Nov 1895, Ørlandet, Norway. I believe Margot's parents were Andreas Olsen(?) (b 6 Oct 1862) and Othelie Marie Olsen (b 10 Aug 1858, Rogaland, Norway). Othelie arrive in Boston on 10 August 1905 and married my great-grandfather, Anton Rønne, on 18 Sept 1905. Margot Olsen Rønne arrives in Halifax, Nova Scotia in April 1907 wither two older brothers Ole and John. The 1910 US Census has Margot and Ole living with Anton and Marie Rønne in Thief Lake Minnesota. I have difficulties using the Digitalarkivet. I believe Othelie Marie's parents were Andreas Olsen and Marie Beathe Nicolaisdotter Tidblad. I also think Othelie Marie may have both legitimate and illegitimate siblings, but I have been unable to track them down. My friend/relative indicates her great-grandmother, Othelie Marie was married to one "Andrew Olsen". Is it possible Othelie Marie's spouse had the same name as her father, Andreas Olsen? Could there be a connection between the two "Andreas/Andrew Olsens"? I know Othelie Marie had children Ole, John and Margot and possibly Anna and Ryborg. Are these children all legitimate with the father Andreas Olsen? If not, who are the other fathers? Are there more siblings? As I indicated before, I have trouble with the Digitalarkivet and I am not certain what I have found is correct, or, not. Any assistance is greatly appreciate. Tom