Wendy I have a lot of data about the Moorfields and can only find the following:-
This Margaret is in my line
Baptisms: 9 May 1819 St Thomas the Martyr, Upholland, Lancashire, England Margaret Moorfield - Child of Richard Moorfield & Betty Abode: UpHolland Occupation: Collier
Marriage: 6 Nov 1843 All Saints, Wigan, Lancashire, England George Brimilow - (X), 27 Collier Bachelor of Pemberton Margaret Moorfield - (X), 24 Spinster of Pemberton Groom's Father: George Brimilow, Carter Bride's Father: Richard Moorfield, Collier Witness: William Atherton; Ann Hindley, (X)
There is another Margaret born in 1819, who was also married on the same day & Church (Hows that for coincidence - maybe there are further connections).:-
Marriage: 6 Nov 1843 All Saints, Wigan, Lancashire, England Thomas Meadows - 25 Weaver Bachelor of Pemberton Margaret Moorfield - (X), 24 Weaver Spinster of Pemberton Groom's Father: Thomas Meadows, Shoemaker Bride's Father: James Moorfield, Weaver Witness: Samuel Winstanley, (X); Ann Boardman, (X)
The fact she was born in Pemberton and that from the 1841 census she has a brother Henry and a sister Jane could point to this being her?
Maybe she reverted to the surname Moorfield following her husbands death or seperation? (Don't think that seperation was allowed then though)
Perhaps you need to look at baptisms for the children christened as Meadows? Do you know which church they used? Only because there are methodist churches in Hindley, as yet not transcribed.