We can see Richard in 1841, living in Boddicott near Banbury, Oxfordshire, England with his wife and a daughter:
Richard Knibb 25 Carrier
Mary Knibb 24
Sophia Knibb 1
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In 1851, Richard is still living at Boddicott with his wife and a son:
Richard Knibs Head Mar 45
Mary Knibs Wife 35
James Knibs Son 8
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Richard appears in the 1861 census, living with his wife and two children aboard the vessel named Emma, at Tunstall, Staffordshire, England:
Richard Knibbs marr 52 Master Oxford Banbury
Mary Knibbs marr 46 Wife Oxford Banbury
James Knibbs unm 18 Son of Master Oxford Banbury
Fanny Knibbs unm 6 Daughter Coventry.

I believe Mary was the daughter of William and Anne Neale from Grimsbury, Oxfordshire, England. Her father was born Jun 1786 and died 24 Jan 1866. Her mother was born at around 1786 and died 20 Mar 1855. After he was widowed, William remarried to Ann Cherry on 4 Oct, 1857 in the Banbury District of Oxfordshire. Mary's father William died at Grimsbury, age 79, cause of death given as natural decay.

We believe that Mary had the following siblings, all born in Grimsbury, Oxfordshire and baptised at Banbury, Oxfordshire.
Elizabeth bap. 3 Jan 1808
Thomas bap. 10 Dec 1809
Eliza bap.16 Feb 1812
James bap. 6 Feb 1814
William bap. 19 Sep 1819
George b. 1822 and d.1822
George bap. 21 Nov 1824
Ann bap. 8 Feb 1829

William and George both married sisters from another boating family, the Drakefords.

In 1841, Mary's parents William and Anne were still living at Grimsbury, and had son George (age 15) still living with them.
In 1851, we can see them both aged 64, living at Grimsbury. William is identified as a laborer born in Adderbury, Oxfordshire.
In 1861, Mary's father William is still living at Grimsbury, but identified as a widower, aged 74, laborer on the road, and born in Adderbury, Oxfordshire.

Thanks to Mark Edwards, a descendant of Mary Neal's brother George, for helping me with the above information.
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Mary can be seen in 1871 living at Tunstall Bridge, Tunstall, Staffs with her second husband James Turner. She married James a couple of years after her husband Richard Knibbs died.
James Turner, Head, 49, Boatman, Farnham Herefordshire
Mary Turner, Wife, 53, Banbury, Oxfordshire
Andrew Turner, Son, Unmarried, 16, Bilston Staffs
Fanny Knibbs, Step-daughter, 16, Domestic Servant, Fosile, Warks
Joseph Wilson, Lodger, Unmarried, 25, Guard on Railways, Staffs
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Mary was given as being aged 46 in the 1861 census and 53 in 1871.
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Mary can be seen in 1891, living at Mow Lane, Congleton, Cheshire with her son-in-law Alfred Wakefield. She is given as Mary Turner, so it is presumed that her second husband James Turner died before 1891.
Alfred Wakefield Head 37 Banksman(?) Cheshire Odd Rode
Fanny Wakefield Wife 35 Coventry Fosile
James H Wakefield Son 14 Bricklayers Labourer Cheshire Odd Rode
Mary E Wakefield 12 Scholar Cheshire Odd Rode
Agnes M Wakefield Daur 10 Scholar Cheshire Odd Rode
Arthur Thos. Son 6 Scholar Cheshire Odd Rode
Edwin M Wakefield Son 2 Cheshire Odd Rode
Mary Turner Mother-in-Law Widow 76 Living on Son in Law Oxfordshire Banbury
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Mary died aged 78 years at Congleton District, Cheshire.

Sophia appears in the birth and death registers as KNIBB.