OK Elizabeth Emma Stuart is probably illegitimate and the Daug of a Susannah Stuart/Stewart.
You may need her Birth Cert to confirm my theory as I cant find a Christening for her
I'll start at the beginning;
MARRIAGE IGI Extracted
John STUART
Mary SELWAY
13 November 1821, Widworthy, Devon
1841 Census
Silon St,
Honiton, Devon,
HO107/200/22/Honiton
John STEWART, 46, Ag Lab
Mary, 40
SUSANNAH, 19
John, 15, Butchers Apprentice
Edwin?, 10
Mary, 7
Nathaniel, 4
Sarah, 6mths
All born in County
1851 Census
Honiton, Devon
HO107/1863/211/46
Mary STUART, 52, Head, Widow, Washerwoman, born Cotleigh
Susanna, 29, Daug, Unm, Dressmaker, born Widworthy
Nathaniel James, 14, Son, Shoemaker, born Ottery St Mary
Sarah, 10, Daug, Lacemaker, born Honiton
William, 6, Son, Scholar, born Honiton
ELIZABETH EMMA, 3, Grand/Daug, born Honiton
On Transcription for Elizabeth Emma Stuart it says "Elizabeth Ann Stuart, 3, born c 1848, Grandson, born Honiton"
When you actually look at the image it is Grand/Daug and Elizabeth Emma Stuart.
1861 Census
High Street,
Honiton, Devon
RG9/1376/33/20
Mary STUART, 63, Head, Widow, Laundress, born Cotleigh
Sarah, 20, Daug, Unm, Lacemaker, born Honiton
William, 17, Son, Unm, Butchers Apprentice, born Honiton
EMMA, 14, Grand/Daug, Unm, Dressmaker, born Honiton
Catherine, 18mths, Grand/Daug, born Honiton