Hi Mo.
Unfortunately I've already ruled her out. She was my last hope.  

These were the three youngest children of Mark Grundy and Margaret Bleasdale. Unless it was bigamous.....and she faked her death.....or there were two of them called Elizabeth....
Marriage: 25 Jan 1868 St Peter, Blackburn, Lancashire, England
Moses Brocklebank - 19 shunterman Bachelor of 36 Thomas St. 
Elizabeth Grundy - (X), 20 weaver spinster of 2 Eanam 
    Groom's Father: John Brocklebank, ostler
    Bride's Father: Mark Grundy, weaver
    Witness: John Loynds; Margaret Loynds, (X)
    Married by Certificate by: W. Hudson
Marriage: 9 Nov 1872 St Mary the Virgin, Blackburn, Lancashire, England
John Grundy - (X), 21 Weaver Bachelor of Trinity St 
Ann Jane Whalley - (X), 20 Weaver Spinster of Adelaide St 
    Groom's Father: Mark Grundy, Weaver
    Bride's Father: Jacob Whalley, Porter
    Witness:
 Moses Brocklebank; Alice Grundy    Married by Certificate by: H. G. Youard
Marriage: 16 May 1875 St Luke, Preston, Lancashire, England
James Middleton - 20 Spinner Bachelor of 42 Deepdale Mill St 
Alice Grundy - 21 Weaver Spinster of 30 Gillett Street 
    Groom's Father: Jacob Middleton, deceased, Spinner
    Bride's Father: Mark Grundy, deceased, Weaver
    Witness: Daniel Caton, (X); Margaret Ann Middleton
Bigamy I can believe - but successfully getting a fake death certificate as well?! Nah. But it's incredibly believable that's the right family. Atkinson st was parallel to crown st.
There's a lot more reason to believe that's the right family - but there's no escaping the double marriage.