William and Eliza were married at St. Giles, Sheldon with Eliza listed as Eliza VINERS, her surname from her first marriage.

William KNIBBS(X), widower, 42, labourer, Sheldon, father Thomas labourer
Eliza VINERS(X), widow, 34, Sheldon, father Thomas labourer
witnesses Harriet WILCOX, Thomas KNIBBS(X)

Identified in the 1851 census for Warwickshire as living at Coleshill, Nr. Birmingham, Warwickshire, Servant.
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We can see William and Sarah living in the Meriden district in 1861:
William Knibbs b.1821 at Woodstock, Oxfordshire, age 40
Sarah Knibbs b.1817 at Dunington, Gloucestershire, age 44
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I have it from Michael Gadd, an Underhill Family researcher that William Knibbs & Eliza Lock appear on the 1871 Census as
Knibs in Sheldon, he is then 57 birthplace not known and she is 45 born at Balsall St. (Balsall Common is not far from Hampton in Arden). The household looks a bit complicated:
Fanny Viner (or Vines) 11 Sheldon
William Knibs 9 Sheldon
Harriet Knibs 6 Sheldon
Clarah Knibs 1 Sheldon
George Knibs Gson 1 Meriden
Roseanah Knibs Gdau 2mo Meriden
(spelling is as it appears on the image - not a transcription).
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The 1881 British Census shows William living at the Cottage, Sheldon, Warwickshire, England with his second wife Eliza, Emma and George (two of Eliza's children from her first marriage) Albert, Florry and George VINNS.
Albert is the youngest child of William and Eliza. Florry, I believe from information passed to me by Hilda Knibbs, was an illegitimate daughter of one of the Viner girls, but was brought up by Eliza. I can only assume that George VINNS (surname as given in the census transcription) was another illegitimate child of one of the Viner girls.
William KNIBBS Head M Male 63 Balsall, Warwick, England Ag Lab
Eliza KNIBBS Wife M Female 63 Balsall, Warwick, England Wife
Emma KNIBBS Daur U Female 29 Sheldon, Warwick, England Visitor
George KNIBBS Son U Male 25 Sheldon, Warwick, England Ag Lab
Albert KNIBBS Son Male 8 Sheldon, Warwick, England Scholar
Florry KNIBBS Daur Female 4 Sheldon, Warwick, England Scholar
George VINNS Grandson Male 11 Sheldon, Warwick, England Scholar

Emma and George are listed as Knibbs so we can assume that they were legally adopted by William as his own.
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There remains some confusion over the birth place of William and Eliza. William we believe is from Woodstock in Oxfordshire and Eliza from Hampton in Arden, Warwickshire. The 1891 census confuses things.

Eliza Knibbs (nee Lock) pictured I would estimate in the late 1870's . She was the second wife of William Knibbs and had herself been previously married to a Edward Viner. (click to enlarge)
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Hilda Elliott (nee Knibbs) has a memorial card for Eliza showing that she died on December 2nd 1910, aged 83. She was interred at Sheldon Parish Church on December 6th.
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It is probably Eliza that appears in the 1901 census for England and Wales, living at Tile Cross, Sheldon, Warwickshire "Living on Own Means". Her birth place is given as Knowles, Warwickshire. It was given as Balsall, Warwickshire in the 1881 census.

Eliza Knibbs 77 Living on Own Means Warwicks Knowles

Died as a young child

Died as a young child

It's understood from Hilda (Knibbs) Elliot, Florry's niece, that Florry wasn't the daughter of William and Eliza Knibbs, but the daughter of one of the Viner girls from Eliza's first marriage to Edward Viner. At this stage, I don't know which of the Viner girls was her mother.