To answer your last question first.The only Mary Jane Gar nett I have was born 1850 and died 1934 in Ontario Can.
Samuel and Martha Garnett had 16 children. Mary Ann, Elizabeth Jane, William Henry, Christopher John,Thomas George, Catherine Louise, Eliza Ellen, Artemisia Uria, Phoebe Edith,Emma Georgene, Ida Minerva, Laura Alberta, Albert Clinton, Charles Alfred, Elsa Adell, Edward Earnest. I know very little about the Watchers, but did have Albert's wife.
I have Samuel and Catherine Allbright Plum(b) as the parents of Martha.
If you would like more information please let me know.