What a difference a decade makes

Censuses can baffle.  A happy family all living together in 1871 in Kyo, Durham were topsy-turvy in-between times and all squeezed up together with barely any shared constituents in 1881.  The surviving thread was Sarah Ann Southern.

1871 Kyo, Durham
William Southern, wife Ann, child Sarah Ann

1881 County Durham
Ann Southern (widow), daughters Sarah Ann, Elizabeth Ann

It appears the two Anns were the same, but no!  The ages nor the birthplace, neither match.  Ann was the *second* wife of William.  So in the space of ten years - a child had been born, the first wife died, a second wife arrived and the father died.  Whew - good going Southerns!

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In Norfolk, Maria Haythorpe's long-awaited death fails to appear, she marries John Brown moments before her death and he remarries, it seems even as the clock chimes the census enumerator's visit.  Not a clue left of that brief relationship.

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In Cornwall, Elizabeth Davies of Hayle helpfully lived with her aunt Sally the entire time, who had a rare name and made pinning them down pretty easy.  One of her daughters married in Dorset, and we're still hunting the other one (Mary).  Elizabeth herself doesn't reveal her death easily - till we find that she too made a deathbed marriage, and is buried under this name - without passing a census year on the way through.
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Picture my surprise at learning our respected uncle Joseph Carline was at the centre of a bitter custody battle over a deceased infant when he was very definitely a grandfather and a widower - or so I thought! Kindly Joseph was a widower in 1861 and on 1871, but not in-between. He'd raced up the aisle of crooked spire Chesterfield church knowing that any child he produced would inherit the sickly bride's lands, even apparently if it later died. He got to work and by 1871 the whole episode had gone, wife, son, land, Chancery case. Until I hauled the surprising paperwork out from the Cheshire mine some time last year. Curiously, his actual grandson a Ford worker at Dagenham was given the infant heir's name and died fairly recently.
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In Somerset, widow Ann Brown was happily living with her children Frecia and Effie and others in 1871.  Ring - bong - all change.  In 1881 the family have apparently reconstituted as:
1881 Ditcheat: William Stride, wife Rachel, stepchildren Annie and Ellen Brown!

What exactly has happened in between!  Only three events have happened this time 'tween the enumerators' call, though we have apparent name changes to deal with. Can you tell what's gone on?