Margaret Hay who I believe died between 1841 and 1851.
Margaret is on the 1841/1851 census.
MARGARET HAY age 60 likely death 10/06/1753 Strichen. (On SP)
Colin
Like you, I assumed that this was the Margaret Hay the OP was referring to - but, through the powers of deduction

- I think we’re actually looking for Margaret MacGillvray (ms Hay), who married James MacGillvray in 1833 in Aberdeen.
Here are the two children referred to in King Edward in 1851:
1851 Crudie Farm
John Mackie, head, 32, Farmer, King Edward
Mary Mackie, wife, 36, King Edward
Janet Mackie, daughter, 5, King Edward
John Mackie, son, 2, King Edward
William Hutcheon, visitor, 34, Farmer, King Edward
Jane Anderson, servant, 17, Gamrie, Banffshire
Ann Hay, servant 14, Monquhitter
James McGillvray, servant, 13, Aberdeen1851 Cook
John Hay, head, 45, Linen Weaver, Monquhitter
Isobel Hay, wife, 41, Monquhitter
Janet Hay, daughter, 16, Monquhitter
Catherine Hay, daughter, 8, King Edward
Christian Roger, mother in law, 69, Monquhitter
Helen Panton, niece, 22, Monquhitter
John McGillivray, cousin, 7, AberdeenI think this may be Margaret McGillvray (ms Hay) and James in 1841:
1841 Flour Mill Brae, Aberdeen
Margaret McGillivray, 25, Shoe Binder, Aberdeenshire
James McGillivray, 3, Aberdeenshire
Ruth