I had a sudden revelation, Edith Lipp was Alberta's mother. I have not found Edith Mortensen or Anna Mortensen in the 1900 Census, but Anna, Alberta & Pearl all show their father was born in Denmark and the children were born in Indiana. So, back to Indiana to find the marriage of Edith to a man named Mortonsen. Have you contacted the Webster District Library in Decatur, Van Buren Co. for marriage records for Anna or Pearl?