It is good that your great uncle has taken a DNA test.
If you have matches with Patons in Ayrshire that is interesting and promising. Your Fred’s father could have come from anywhere couldn’t he?
Are they close matches?
Highest seems to be 39cM so not sure really
Going from the public member trees, George gallacher paton seems interesting, lists him as a gardener, 10 years older than jeannie and married, cant place him in Aberdeenshire at all
1891 census puts him in west linton, peebleshire, address says gardeners bothy, garvald, occupation gardener
He had children born in 1898 and 1899 in Edinburgh so seems unlikely he was in Aberdeenshire