Becky,
From your reply, it is most definitely the same family!
I have actually sat and looked through the hand written parish
records for Chatteris (I live about a 2 hour drive away from
the record office).

The entry for the marriage of Daniel & Mary reads :-

1850 Apr 14
Daniel Ruston (x) 25 bach lab son of Richard lab
Conquest Mary (x) 28 spin d of Henry lab
Wit:- Farmer Ruston, Robert Martin (wit on most marriages)

basically the (x) means that neither could sign their own names when they married. Which may account for the biography being wrong.

Also there are 4 other marriages in the Chatteris registers which have links with Daniel & Mary (and numerous births).

Apr 8 1849 - (Mary's sisters marriage)
Gowler Thomas(x) bac lab s of John lab
Conquest Caroline(x) sp d of Henry lab
Wit: Daniel Ruston(x), Robert Martin

Nov 17 1856 - (Mary's brothers marriage)
Conquest Thomas bac lab s of Henry lab
Webb Emma sp d of William butcher
Wit: Walter Web,Rhoda Webb,William Feast,Susan Smith

Nov 24 1862 - (Mary's sisters marriage)
Parker Henry (x) 21 bac lab s of John lab
Conquest Elizabeth (x) 22 sp d of Henry lab
Wit: John Blackburn (x), Charlotte James(x)

Apr 28 1878 - (Elizabeth's illegitimate daughter - born in workhouse ie. Mary's niece)
Shaw Owen 19 bac lab s of John lab
Conquest Ann 19 sp d of (blank)
Wit:Thomas Gowler, Harriet Shaw

The icing on the cake for me would be to find out who Mary's
mother was !. I have only found one possible entry for
Keziah Conquest marrying Henry Conquest.

What information would the death certificate hold ?
Also do you know how the family travelled to the U.S. ?

Regards
Susan Ling