Looking for Mary Stead

[Coldstream Lynn]

I am looking for Mary Stead in 1841/51/etc. She was the sister of my ggg grandmother Elizabeth Stead c 1830, who was born in Bishop Wilton/Kirby Underdale/Kexby, depending on the census. According to Elizabeth's marriage cert, their father was Edward Stead Labourer
Mary had an illegitimate son Thomas Jackson Foster Stead in 1859 in Hull. He then went to live with his aunt Elizabeth.
I am trying to find Mary in the hope that I can find the rest of their family, as I have been unable to locate Elizabeth prior to her marriage in 1859.