This looks like the family you mention on
https://www.scotlandspeople.gov.uk Marriage 1778.
SAMUEL FERGUSON MARRIED MARGARET MCMICHEL 06/09/1778 KEIR
Children’s baptisms
FERGUSON JOHN SAMUEL FERGUSON/MARGRET MCMICHEL 17/06/1779 KEIR
FERGUSON JAMES SAMUEL FERGUSON/ 12/12/1780 KEIR
FERGUSON WILLIAM SAMUEL FERGUSON/ 11/11/1782 KEIR
FERGUSON JOSEPH SAMUEL FERGUSON/ 12/08/1789 KEIR
FERGUSON MARGARET SAMUEL FERGUSON/ 18/04/1785 KEIR
FERGUSON JEAN SAMUEL FERGUSON/ 19/03/1787 KEIR
FERGUSSON GRISSEL SAMUEL FERGUSSON/MARGARET MCMICHALL 27/04/1792 KEIR
FERGUSSON ROBERT SAMUEL FERGUSSON/MARGRET MCMICHALL 09/05/1794 KEIR
Possible baptism for Margaret.
MCMICHAEL MARGRET JAMES MCMICHAEL/MARGRET GIBSON) F 04/08/1754 PENPONT
Penpont, Dumfriesshire is 8 miles NW of Keir, Dumfriesshire
I cannot see a baptism on SP in the County for Samuel but if they followed the Scottish naming pattern it would likely be John as his father, however not all did, the best alternative I can find is in Ayrshire.
FERGUSSON SAMUEL WILLIAM FERGUSSON 25/04/1756 KIRKOSWALD
Colin
PS: Not all family trees are correct, it is better to substantiate them with evidence.