Charlotte Knapp was probably the mother of William Cable so probably 2nd great grandmother.
Charlotte’s husband Jonathan Cable was definitely the father of William Cable, who was father of Gladys Cable. Jonathan was married first to Eliza, after her death he married Charlotte. Jonathan and Eliza were definitely the parents of John Cable, John’s death certificate proves this. The mother of the younger Cable children Chancey, William, Sarah and Violetta is not definite. Most likely Chancey’s mom was Eliza and Charlotte Knapp was the mom of William, Violetta and Sarah. No records prove this, on some records William’s mother is Eliza, on others his mother is Charlotte.
If Charlotte Knapp is the mother of William Cable, his ancestors go all the way back to the 1630s Winthrop Fleet, 11 ships that sailed from England to America.
For sure Charlotte was born in New York around 1831 and married a first husband. Then as a single woman (widowed, divorced) she joined her brothers and sisters in Dane County, Wisconsin where around 1850 she married William Cable, there is no marriage source. In 1870 Jonathan age 60, Charlotte age 36, Chancey age 20, William age 18, Sarah age 15 and Violetta age 13 live in Pleasant Grove, Floyd County, Iowa.
Charlotte and Jonathan were Methodists and helped get a church started in Pleasant Grove in the summer of 1867. “A gentleman named Swan … was the first preacher during the summer of 1867. The next summer Methodists of Charles City sent one of their local preachers … at the first meeting there were about fifteen present, including Jonathan Cable’s family. Link to History of Floyd County, Iowa on HathiTrust
In 1885 Charlotte’s dad William Knapp lived with the Cable family. 1885 Floyd, Pleasant Grove, Iowa the Iowa census, Cable, Jonathan, Charlotte, William and William Knapp screenshot.
Charlotte most likely died in Chicago on June 2, 1899 and is buried in Dane, Wisconsin near her brothers, sisters and mom, Rhoda Bowers in a tiny, very rural cemetery in the middle of cornfields, link to Google maps location. Her husband Jonathan Cable’s death and burial info are unknown.