I am also researching this line of Cambridges. Specifically my grandmother, Dana Cambridge b.1882, in Iowa and travelled to Idaho about 1887. Her great uncles were Silas and Middleton (Milton) Cambridge. (sons of John F.Cambridge and Susannah Petty.) However, she never knew who her mother was. My "theory" is that she may have been a child of Almeda Cambridge, perhaps born out of wedlock. I am running out of hope that I will ever figure this out, but what an interesting family to research!