Mary Ann Dyson

[rosie99]

but Joseph's father was Samuel. That has all been verified.

What do you have that states Joseph's father was Samuel 

I suspect that the reason you can't find Dora in 1871 is that the census enumerator has listed her wrongly as David, unless you have later evidence that there was a David as well.  I can't see a birth registration or baptism for him.

Rosie

[rosie99]

Marriage:
9th August 1863 Wath upon Dearne
Mary Ann Myers age 24, spinster. Father George Myers, blacksmith
Joseph Wadworth age 21, puddler. Father George Wadworth

George Dyson was also a blacksmith.

The witnesses were Richard Griffiths & Elizabeth Griffiths - Richard Griffiths married Elizabeth Dyson in 1857 at Wath - her father was George Dyson a Blacksmith. 

I would say that this is the marriage you are looking for.