Hi Lance,
Hi Iain, I am researching the Sutherland family, specifically Archibald Sutherland who married a Janet Donald in the  1760's, possibly in Banff as their children, George, Hugh, Isabella, Robert, Elizabeth and Jean were born in Mortlach between 1769 and 1781.
Thanks for your time, cheers, Lance
I hope you have had some luck in your search. I've been looking at Mortlach Donalds tonight. Here is a list of the early (pre-1800) baptisms in Mortlach, along with abodes and related witnesses:
ROBERT DONALD   -   ELSPET MITCHEL
1742   Robert, Enoch
1745   Elisabeth, Enoch
1747   Isobel, Little Enoch
1748   Josep, Enoch
ROBERT DONALD   -   ISOBEL MILNE
1744   Margaret, Tambally, w. Alex'r Donald there
1746   Janet, Tambally
JOHN DONALD   -   JEAN STUART
1743   Alexander, Tomballie
1745   Isobel, Tambally
1747   James, Tambally, w. James Donald, Enoch
1752   John, Tambally, w. John Donald, Enoch
1759   Robert, Tambally, w. Robert Donald there
JAMES DONALD   -   ELSPET THOMSON
1765   James, Enoch, w. James Donald there
1767   Margaret, Little Enoch, w. Rob't Donald jun'r, Tomballie
1769   Elizabeth, Little Enoch
ROBERT DONALD   -   JEAN MITCHEL
1768   John, Tomballie, w. John Donald, Tomballie
1769   Isobel, Tomballie, w. Jno Donald, Enoch
1772   Elspet, Tomballie, w. John Donald
1774   Alexander, Nether Tomballie, w. Alexander Donald, Laggan
1777   Jean, Tomballie, w. Alexander Donald, Tomballie
1779   Robert, Enoch, w. Alexander Donald Tamballie; John Donald, Enoch
ALEXANDER DONALD   -   ELISABETH DONALD
1786   Alexander, Little Enach
I notice that Robert Sutherland's 1776 baptism notes Robert Donald of Tomballie as a witness. I have an extensive family tree for him. It's likely that he was your Janet Donald's relation. Your Janet Donald may then be Janet Donald, b. 1746, in Tambally, daughter of Robert Donald and Isobel Milne. It's speculative, but it might give you something to work with.
Best of luck,
Iain.